Inject markdown syntax for rust doc_comments

[A-Walrus]

Describe your feature request

Since rust doc comments support markdown it would be nice to highlight it as such. Especially useful for code within doc comments for which the language should be injected into the markdown which is injected into rust.

[CptPotato]

If implemented I would prefer this to be optional. Having full markdown highlighting in comments would probably distract me a lot from the actual code.

[kirawi]

https://github.com/tree-sitter/tree-sitter-rust/issues/130

[the-mikedavis]

https://github.com/tree-sitter/tree-sitter-rust/pull/168 looks promising for this. It works the same as https://github.com/helix-editor/helix/pull/4870