Add meta repo files

[feydan]

We should document some of the following to encourage and guide contributions:

• Contributor file
• Issue creation templates and advice

[hernandezforges]

@wincowgerDEV The templates can be done with .md and .txt extensions. Got this info from GitHub Docs: https://docs.github.com/en/communities/using-templates-to-encourage-useful-issues-and-pull-requests/about-issue-and-pull-request-templates

[wincowgerDEV]

Thanks for this! Will try to implement this before the manuscript review deadline too.