Improve front-facing documentation

[No767]

Summary

This PR focuses on improving the CONTRIBUTING.md and README.md documents. Although other documentation (including the setup docs) are not written yet (waiting on domain name change), they will be added later.

Types of changes

What types of changes does your code introduce to Kanae?
Put an x in the boxes that apply

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (Updates to README.md, the documentation, etc)
• Other (if none of the other choices apply)

Checklist

Put an x in the boxes that apply

• If code changes were made then they have been tested.
  • I have updated the documentation to reflect the changes. (if appropriate)
• All workflows (except pre-commit.ci) pass with my new changes
• This PR does not address a duplicate issue or PR