Use Comments above functions in signature completion?

[FourierTransformer]

I feel like in Lua/Teal folks put comments about any relevant info above the method itself (either as LDoc or just as a comment). Maybe we can check the lines before a function type reference and see if it's a comment. I haven't looked through the Teal data structures enough to know if comments are available or not, but might be useful.

Could also expand into parsing LDoc and displaying it nicely.