Self-hosting docs are outdated and point to legacy `happy-server` setup？

[afghl]

The self-hosting guide appears to be outdated:

https://happy.engineering/docs/guides/self-hosting/

Current issues I noticed:

It tells users to clone https://github.com/slopus/happy-server, but the current server code lives in the main monorepo: https://github.com/slopus/happy.