message: add section on where to find libs team
diff: # Libs
  -This section documents meta processes by the libs team.
  +This section documents meta processes by the Libs team.
  +
  +## Where to find us
  +
  +The libs team hangs out primarily in [the rust-lang Zulip](https://rust-lang.zulipchat.com/) these days in the `#t-libs` stream.
  +
  +The `#rustc` IRC channel on `irc.mozilla.org` is in a "quasi-deprecated" status and is not recommended.
  