[docs] [issue38352] In typing docs, note explicit import needed for IO and Pattern/Match

Jelle Zijlstra <jelle.zijlstra@gmail.com> added the comment: @Łukasz thanks for your merging spree! I'm actually not sure this should go into 3.9. Seems potentially dangerous that people upgrading from an earlier 3.9 patch release will now see new names injected into their namespace if they do `from typing import *`. ---------- _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue38352> _______________________________________