Add License, CoC, and a footer

[danfishgold]

A bunch of stuff we need to apply to Netlify's open source plan:

• A license file (MIT)
• A code of conduct (which mainly refers to the one on our website)
• A footer with a link to Netlify (and a link to the repo)

[netlify[bot]]

✔️ Deploy Preview for crc-annotations ready!

🔨 Explore the source changes: 3ed6559ffbad2c60e62a4f7791942aaff91202f3

🔍 Inspect the deploy log: https://app.netlify.com/sites/crc-annotations/deploys/61fed91132ca040007d6d4e3

😎 Browse the preview: https://deploy-preview-20--crc-annotations.netlify.app/

[katjam]

Merge away!