Highlight zig in mardown code blocks

[matklad]

Currently zig is not highligheted in markdown:

Here's an example to make it work:

https://github.com/mjbvz/vscode-fenced-code-block-grammar-injection-example

[SuperAuguste]

This is probably an issue for https://github.com/ziglang/vscode-zig as we don't provide highlighting grammars (though maybe we should start doing so?)

[matklad]

though maybe we should start doing so?

I think that's the way. More generally, I believe there shouldn't be separate zig and zig-zls vscode extensions, there should be a single extension that handles everything zig-related. From the user's perspective, an important part of UX is to be able to install a single thing, and trust the authors of the thing to correctly assemble a holistic user experience from the underlying tools.

To clarify, this integration would not preclude someone from shipping an alternative view of how it all should look like: the benefit is in integration, not in monopoly.