docs: update README files to add API Reference link for new packages

[rainx]

1. Add API Reference link to README file for date-helpers package.
2. update the title of the API Reference of the exceptions package to API Reference (before it is called Modules )

Pull Request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Build-related changes
• Documentation content changes
• Other (please describe):

Does this introduce a breaking change?

• Yes
• No

[github-actions]

Pull Request closed and locked due to lack of activity.
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