Split docs from the README into a searchable site

[javeoff]

Your README covers install, features, PWA setup and self-hosting in one long scroll. Fine to read top to bottom, hard to link someone straight to "how do I self-host this."

Split it into pages with search here: https://docsbook.io/n-ce/ytify

Didn't touch your repo, this just renders the same content differently. Ignore it if you're not looking for this, figured it's easier to show than describe.