Generate docs via CI

Right now https://www.x.org/releases/current/doc/index.html and all the docs under it are manually generated and posted every time we roll up a new katamari release. Which means they're now 6 years old and missing all the extension changes since then.

It would be nice if we could have CI just autopublish the docs there - we might still have to manually maintain the index.html page, but getting updated specs & API docs would be awesome.