docs: Put specific ignore comment for missing types

[yedayak]

The docs for "Missing library stubs or py.typed marker" give you an option to ignore the error, but its not complete. Copying it verbatim into your code results in this error:

error: "type: ignore" comment without error code (consider "type: ignore[import-not-found]" instead)  [ignore-without-code]

The error is helpful, but just having it work right away will be better :)

[wyattscarpenter]

This only happens because you have ignore-without-code enabled; presumably from running mypy in strict mode.

It seems fine and better to specify the exact ignore code here, though.