Add markdown code block syntax highlight support

[wangbinyq]

No description provided.

[chenglou]

Hey, thanks! Though is this the idiomatic way of doing it? It seems typescript's grammar repo doesn't have such thing?

[wangbinyq]

I rewrite the file from the vscode-reasonml repo, just some minor changes.

[fhammerschmidt]

@zth can we get semantic highlighting in markdown blocks as well?

[zth]

@fhammerschmidt I'm not sure. Does TS do it?

[aspeddro]

I was looking for how vscode apply syntax highlighting in markdown. It doesn't use semantic highlighting just TexMate grammar.

Here are supported languages.

[fhammerschmidt]

Having at least a bit of highlighting would already be nice.
Currently it is just all the same color.

[zth]

I'm thinking we should merge this as is. I agree that some highlighting is better than none. Ok with you @cristianoc ?

Side note: There's more interesting things we can do eventually to better support md, like formatting code inside of ReScript md blocks.