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

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branch : 3.4
extra : rebase_source : 26e0909a455d2a8ee29ab5e99cd193084ddcd8cc
make plural s lowercase

--HG--
branch : 3.3
merge 3.3

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

Patch by Févry Thibault.

--HG--
branch : 3.4