Improve Docs DX

[jsimonrichard]

The docs are already decent; I especially appreciate the long prose sections describing the general framework of the codemirror, lezer, etc. However, they can be hard to navigate at times, and they're missing some modern features that would be really nice:

• Full-text search (including the examples and prose sections, not just the reference manual)
  • For someone who's unfamiliar with the project, this would be really helpful. Ex: I'm trying to figure out how to access the most recent EditorSelection object; when I search EditorSelection, I only get its type definition, not the selection property on EditorState.
  • I know you might be able to achieve this with site:codemirror.net on Google, but having an integrated full text search (like Astro has) would be much better.
• Links from the reference API docs to the source code on github. I often will read the source code of functions I have questions about, but as it's currently implemented, I have to go hunting on GitHub to try to find it.

One possible way to implement it would be with something like Astro and Starlight (Including the TypeDoc plugin). I'm sure there are other ways out there I'm not aware of.

I imagine this would be a fair amount of work. I don't have time right now, but I'd love to help with this if I can.