[feature request] Provide embedded language markdown for doc attributes

[alanz]

This has been enabled in vscode, and I see emacs 30 and beyond support Multiple Languages.

On the face of it, it seems like it just needs a treesit-range-settings entry and an implementation of treesit-language-at-point-function that detects the context from a wild attribute, with a name atom of doc.

[alanz]

I made a small attempt at this, modelling it on the elixir and heex embedded language.
And hit a brick wall where markdown-ts-mode won't install the grammar for emacs 30 because it has ABI 15, and emacs is still 14.

So this may have to wait for the next emacs release, or an ABI version workaround

[alanz]

Related issue on the markdown treesitter grammar. tree-sitter-grammars/tree-sitter-markdown#199

[dgud]

I would appreciate a PR implementing this :-)

[alanz]

When I get time, I will give it a go

[bbatsov]

We're using the embedded markdown grammar in clojure-ts-mode and it works fine on Emacs 30 https://github.com/clojure-emacs/clojure-ts-mode/pull/79/files

But admittedly there's a lot of room for improvement in Emacs's support for Tree-sitter today.