[Feature Request] Add additional fields to exported docs

Nobody has claimed this yet.

Right now, it's very difficult to parse the exported docs. I've mostly been able to figure stuff out, but there's a bit of information the exported JSON file does not expose, which I would like to suggest.

- A field for which class something originates from, to filter out unchanged methods/fields from parents
- A relative version of `file`, instead of an absolute path
- [x] A version of the description which does not include markdown for params and return values, since those are separate
- Whether a function is deprecated or not
- A way to hide a field or method from the docs export (`---@nodoc`?)
- Maybe a way to not export inherited fields/methods? The exported file for my project is more than a million lines long...

Start by locating the exported documentation JSON implementation and the code that assembles fields for functions, methods, and fields. Review how inheritance, file paths, descriptions, and deprecation are currently represented; done would require an agreed scope and tests covering the selected export fields and nodoc or inheritance behavior.

Written by the indexing model from the issue text.