WASI notification group

Github Label: O-wasi
Ping command: @rustbot ping wasi

This list will be used to ask for help both in diagnosing and testing WASI-related issues as well as suggestions on how to resolve interesting questions regarding our WASI support.

The group also has an associated Zulip stream (#t-compiler/wasm) where people can go to pose questions and discuss WASI-specific topics.

So, if you are interested in participating, please sign up for the WASI group! To do so, open a PR against the rust-lang/team repository. Just follow this example, but change the username to your own!