📝 Docs: Document broader Mocha project resources

[mark-wiemer]

Documentation Request Checklist

• I have read and agree to Mocha's Code of Conduct and Contributing Guidelines
• I have searched for related issues and issues with the faq label, but none matched my issue.
• I want to provide a PR to resolve this

Overview

For end users: What resources can they use to contact us or learn more about Mocha? (Discord, mochajs.org, GitHub org and its repos)

For new contributors:

• external resources: what are things like Codecov and EasyCLA? What other cloud services do we use that they might want to know about?
• in-repo resources: what does /.fossaignore do? What about other weird config files? What tooling does Mocha use in-repo to keep itself clean? What scripts should new contributors know about?

For admins: What is our relationship to Open Collective or OpenJS Foundation? What about other funding sources or infrastructure like Netlify? Who, if anyone, do we pay, and why?

Additional Info

In alphabetical order:

• Codecov
• Discord
• EasyCLA
• GitHub org
• GitHub Sponsors
• mochajs.org
• OctoGuide
• Open Collective
• OpenJS Foundation
• Netlify for site hosting (Mocha admins only
• Renovate by Mend
• Tidelift

[JoshuaKGoldberg]

What if we added a dedicated section to the site? For reference, I've previously set up https://typescript-eslint.io/contributing & https://typescript-eslint.io/maintenance for similar purposes.