Document requirement for static linking with Wasm

[gushogg-blake]

I think #93 is caused by the fact that the custom scanner uses functions that aren't in Tree-sitter's main exports.json file (see tree-sitter/tree-sitter#949).

I've outlined a workaround here - https://edita.vercel.app/blog/tree-sitter-howto/

When I was last looking into this Max hadn't decided on an approach to fixing it so might be a good idea to include a note in the readme that it needs a workaround for now.

[clason]

This should ideally be fixed by adding the missing symbols to tree-sitter: tree-sitter/tree-sitter#1864 (comment) (if they're critical; otherwise it's probably easier to try to rewrite the scanner without them @amaanq)

Now that WASM parsers are officially supported by tree-sitter (C library), this has become a more pressing issue.