React API Documenter

Like @microsoft/api-documenter, but more tailored to React libraries.

Generates markdown files usable with Docusaurus, from an api.json file created by @microsoft/api-extractor.

@microsoft/api-documenter is great, but in the context of React libraries, its output can be improved:

- It groups exports under categories, that would make more sense if they were more specific (e.g. _Functions_ => _Hooks_, _Components_, _Functions_)
- It creates one page per export, but the documentation would be more usable if Components and their props were grouped in a single page.