feat(doc): generate meta file

[lewis6991]

This file adds additional logic to docgen.lua to generate a file meta.lua which is formatted with LuaCATs.

For complex types, the script will automatically create either a @class or @alias, and will be rendered near to their use.

---

Note: This PR produces something similar to https://github.com/LuaCATS/luv, but not 100%. The main difference being that this PR generates significantly less @class and @alias names.

[clason]

Seems to be missing uv.read_start.callback (and friends)?

[lewis6991]

Yes, I chose not to generate these. For simple types they are inlined.

--- @param stream uv.uv_stream_t
--- @param callback fun(err: string?, data: string?)
--- @return 0? success
--- @return string? err
--- @return string? err_name
function uv.read_start(stream, callback) end

[clason]

Ok, but that means these files are not drop-in replacements for https://github.com/LuaCATS/luv, and switching to them requires annotation changes in Neovim (_system.lua, to be precise).

[lewis6991]

Yes. Providing a 100% drop-replacement for https://github.com/LuaCATS/luv was not my intended goal

[clason]

That's fair, but could you then make the goal explicit in the PR description (which I suspect is garbled; the second paragraph doesn't make sense to me)?

[lewis6991]

I think the current PR description reflects the goal and makes no mention of https://github.com/LuaCATS/luv . However, I've added a note mentioning it is similar but different.

[lewis6991]

cc @truemedian @squeek502 . Sorry to ping, any chance of a review?

[squeek502]

docs.md changes look good, and I'm going to trust that the meta.lua file is useful for the intended use cases as I'm unfamiliar with LuaCATS.

Thanks!