breaking_change: Replace M.config.highlights with M.config.groups

The `highlight` configuration option is deprecated. Please use the
`groups` option instead. Refer to the updated documentation in the
'configuration' section of the README.md.

Additionally, this commit resolves the transparency issue caused by the
incorrect implementation of the `M.config.options.transparent` option.

CODE_OF_CONDUCT.md

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+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+We as members, contributors, and leaders pledge to make participation in our
+community a harassment-free experience for everyone, regardless of age, body
+size, visible or invisible disability, ethnicity, sex characteristics, gender
+identity and expression, level of experience, education, socio-economic status,
+nationality, personal appearance, race, religion, or sexual identity
+and orientation.
+
+We pledge to act and interact in ways that contribute to an open, welcoming,
+diverse, inclusive, and healthy community.
+
+## Our Standards
+
+Examples of behavior that contributes to a positive environment for our
+community include:
+
+* Demonstrating empathy and kindness toward other people
+* Being respectful of differing opinions, viewpoints, and experiences
+* Giving and gracefully accepting constructive feedback
+* Accepting responsibility and apologizing to those affected by our mistakes,
+  and learning from the experience
+* Focusing on what is best not just for us as individuals, but for the
+  overall community
+
+Examples of unacceptable behavior include:
+
+* The use of sexualized language or imagery, and sexual attention or
+  advances of any kind
+* Trolling, insulting or derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or email
+  address, without their explicit permission
+* Other conduct which could reasonably be considered inappropriate in a
+  professional setting
+
+## Enforcement Responsibilities
+
+Community leaders are responsible for clarifying and enforcing our standards of
+acceptable behavior and will take appropriate and fair corrective action in
+response to any behavior that they deem inappropriate, threatening, offensive,
+or harmful.
+
+Community leaders have the right and responsibility to remove, edit, or reject
+comments, commits, code, wiki edits, issues, and other contributions that are
+not aligned to this Code of Conduct, and will communicate reasons for moderation
+decisions when appropriate.
+
+## Scope
+
+This Code of Conduct applies within all community spaces, and also applies when
+an individual is officially representing the community in public spaces.
+Examples of representing our community include using an official e-mail address,
+posting via an official social media account, or acting as an appointed
+representative at an online or offline event.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be
+reported to the community leaders responsible for enforcement at
+[email protected].
+All complaints will be reviewed and investigated promptly and fairly.
+
+All community leaders are obligated to respect the privacy and security of the
+reporter of any incident.
+
+## Enforcement Guidelines
+
+Community leaders will follow these Community Impact Guidelines in determining
+the consequences for any action they deem in violation of this Code of Conduct:
+
+### 1. Correction
+
+**Community Impact**: Use of inappropriate language or other behavior deemed
+unprofessional or unwelcome in the community.
+
+**Consequence**: A private, written warning from community leaders, providing
+clarity around the nature of the violation and an explanation of why the
+behavior was inappropriate. A public apology may be requested.
+
+### 2. Warning
+
+**Community Impact**: A violation through a single incident or series
+of actions.
+
+**Consequence**: A warning with consequences for continued behavior. No
+interaction with the people involved, including unsolicited interaction with
+those enforcing the Code of Conduct, for a specified period of time. This
+includes avoiding interactions in community spaces as well as external channels
+like social media. Violating these terms may lead to a temporary or
+permanent ban.
+
+### 3. Temporary Ban
+
+**Community Impact**: A serious violation of community standards, including
+sustained inappropriate behavior.
+
+**Consequence**: A temporary ban from any sort of interaction or public
+communication with the community for a specified period of time. No public or
+private interaction with the people involved, including unsolicited interaction
+with those enforcing the Code of Conduct, is allowed during this period.
+Violating these terms may lead to a permanent ban.
+
+### 4. Permanent Ban
+
+**Community Impact**: Demonstrating a pattern of violation of community
+standards, including sustained inappropriate behavior,  harassment of an
+individual, or aggression toward or disparagement of classes of individuals.
+
+**Consequence**: A permanent ban from any sort of public interaction within
+the community.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage],
+version 2.0, available at
+https://www.contributor-covenant.org/version/2/0/code_of_conduct.html.
+
+Community Impact Guidelines were inspired by [Mozilla's code of conduct
+enforcement ladder](https://github.com/mozilla/diversity).
+
+[homepage]: https://www.contributor-covenant.org
+
+For answers to common questions about this code of conduct, see the FAQ at
+https://www.contributor-covenant.org/faq. Translations are available at
+https://www.contributor-covenant.org/translations.

CONTRIBUTING.md

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+# Contributing
+
+We want to make contributing to this project as easy and transparent as possible, whether it's:
+
+- Reporting a bug
+- Discussing the current state of the code
+- Submitting a fix
+- Proposing new features
+- Becoming a maintainer
+
+## Code of Conduct
+
+See [CODE_OF_CONDUCT.md](CODE_OF_CONDUCT.md)
+
+## I am not a developer
+
+Do not worry, you can still contribute fixing the documentation or just opening the issues and reporting bugs!
+Do not underestimate your impact, as the job of tester and bug triager is one of the most valuable in any software project.
+What the use of being a developer if you don't know what to fix or implement?
+
+## Development Packages
+
+To make sure you can develop the theme install all the tools you need:
+
+- [neovim-nightly](https://github.com/neovim/neovim/releases/tag/nightly)
+- [lua-language-server](https://github.com/neovim/nvim-lspconfig/blob/master/doc/server_configurations.md#sumneko_lua) must be setup in neovim
+- [StyLua](https://github.com/JohnnyMorganz/StyLua)
+
+## Our Development Process
+
+We use GitHub to sync code to and from our internal repository. We'll use GitHub to track issues and
+feature requests, as well as accept pull requests.
+
+## Pull Requests
+
+We actively welcome your pull requests.
+
+1. Fork the repo and create your branch from `main`.
+2. If you've added code that should be tested, add tests.
+3. If you've changed Look, update the documentation.
+4. Make sure your code lints.
+5. Issue that pull request!
+
+## Styleguides
+
+### Lua Styleguide
+
+All lua code is linted with StyLua.
+
+- 2 spaces for indentation rather than tabs
+- Use Single quotes for string
+- Use [EmmyLua Annotations](https://emmylua.github.io/annotation.html)
+
+### Documentation Styleguide
+
+- Use [Markdown](https://daringfireball.net/projects/markdown/).
+
+### Git Commit Message Guidelines
+
+A properly formed git commit subject line should always be able to complete the following sentence
+
+If applied, this commit will <your subject line here>
+
+### Git commit message style
+
+- **Do not use emojis**
+- Consider starting the commit message with an applicable abbreviation:
+
+  - `feat:` When improving the format/structure of the code
+  - `breaking_change:` When potentially breaking changes made to original functionality
+  - `deprecated:` for deprecated feature commit
+  - `fix:` When fixing a bug
+  - `refactor:` for refactoring production code, e.g. renaming a variable.
+  - `chore:` updating grunt tasks etc; no production code change.
+    "grunt task" means nothing that an external user would see:
+    - implementation (of an existing feature, which doesn't involve a fix),
+    - configuration (like the .gitignore or .gitattributes),
+    - private internal methods...
+  - `perf:` for performance improvements.
+  - `style:` for formatting changes, missing semicolons, etc.
+  - `test:` for adding missing tests, refactoring tests; no production code change.
+  - `docs:` When writing documentation
+  - `ci:` for CI GitHub Actions related tasks.
+
+- Separate subject from body with a blank line
+- Do not end the subject line with a period
+- Capitalize the subject line and each paragraph
+- Use the imperative mood in the subject line
+- Wrap lines at 72 characters
+- Use the body to explain what and why you have done something. In most cases, you can leave out details
+  about how a change has been made.
+
+### Information in commit messages
+
+- Describe why a change is being made.
+- How does it address the issue?
+- What effects does the patch have?
+- Do not assume the reviewer understands what the original problem was.
+- Do not assume the code is self-evident/self-documenting.
+- Read the commit message to see if it hints at improved code structure.
+- The first commit line is the most important.
+- Describe any limitations of the current code.
+- Do not include patch set-specific comments.
+
+Details for each point and good commit message examples can be found on
+[wiki.openstack.org](https://wiki.openstack.org/wiki/GitCommitMessages#Information_in_commit_messages)
+
+### References in commit messages
+
+If the commit refers to an issue, add this information to the commit message header or body. e.g. the
+GitHub web platform automatically converts issue ids (e.g. #123) to links referring to the related issue.
+
+In header:
+
+`[#123] Refer to GitHub issue…`
+
+In body:
+
+```
+
+…
+Fixes #123, #124
+```
+
+## Issues
+
+We use GitHub issues to track public bugs. Please ensure your description is clear and has sufficient instructions
+to be able to reproduce the issue. If possible please provide a minimal demo of the problem.
+
+## Issue Triage
+
+Here are some tags that we're using to better organize issues in this repo:
+
+- `!` - Bug or issue has be opened for more than a week
+- `!!` - Bug or issue has be opened for more than a month
+- `assigned` - Under progress.
+- `bug` - Something isn't working
+- `documentation` - Relating to improving documentation for the project.
+- `duplicate` - This issue or pull request already exists
+- `enhancement` - New feature or request
+- `good first issue` - Good candidates for someone new to the project to contribute.
+- `help wanted` - Issues that should be addressed and which we would welcome a PR for but may need significant
+  investigation or work
+- `question` - Something that is a question specifically for the maintainers.
+
+## Bug reports
+
+Great Bug Reports tend to have:
+
+- A quick summary and/or background
+- Steps to reproduce
+  - Be specific!
+  - Give sample code if you can.
+- What you expected would happen
+- What actually happens
+- Notes (possibly including why you think this might be happening, or stuff you tried that didn't work)
+
+People love thorough bug reports. We're not even kidding.
+
+## License
+
+By contributing, you agree that your contributions will be licensed under its `MIT` License.
+
+## References
+
+- [atom/CONTRIBUTING.md](https://github.com/atom/atom/blob/master/CONTRIBUTING.md)
+- [robertpainsi/commit-message-guidelines.md](https://gist.github.com/robertpainsi/b632364184e70900af4ab688decf6f53)
+- [draft-js/CONTRIBUTING.md](https://github.com/facebook/draft-js/blob/main/CONTRIBUTING.md)
+- [bismuth/CONTRIBUTING.md](https://github.com/Bismuth-Forge/bismuth/blob/master/CONTRIBUTING.md)