Closes #22663: patchcheck: only modify text files under Doc/

--HG--
branch : 3.4
extra : rebase_source : 26e0909a455d2a8ee29ab5e99cd193084ddcd8cc
merge with 3.4
make plural s lowercase

--HG--
branch : 3.3
merge 3.3

--HG--
branch : 3.4
merge 3.4
Issue #22186: Fix typos in Lib/.

Patch by Févry Thibault.

--HG--
branch : 3.4
Issue #22186: Fix typos in Lib/.

Patch by Févry Thibault.
Close #19746: expose unittest discovery errors on TestLoader.errors

This makes it possible to examine the errors from unittest discovery
without executing the test suite - important when the test suite may
be very large, or when enumerating the test ids from a test suite.