Fix all-contributors file.

[chrisgavin]

Why:

The syntax of the .all-contributorsrc file seems to have been broken at some point and is no longer valid JSON.

What's being changed:

The structure of file has been fixed. I've also regenerated the readme to make it consistent with the .all-contributorsrc file again.

Check off the following:

• All of the tests are passing.
• I have reviewed my changes in staging. (N/A)
• For content changes, I have reviewed the localization checklist (N/A)
• For content changes, I have reviewed the Content style guide for GitHub Docs. (N/A)

[welcome]

Thanks for opening this pull request! A GitHub docs team member should be by to give feedback soon. In the meantime, please check out the contributing guidelines.

[janiceilene]

Thanks for fixing this up 💝

[github-actions]

Thanks very much for contributing! Your pull request has been merged 🎉 You should see your changes appear on the site in approximately 24 hours.

If you haven't already, you can add yourself to the list of contributors by creating a new comment in this PR using these instructions. Thanks again! ✨