Fix typo in `__match_args__` doc (GH-99785)

A opy of GH-98549, whose author (@icecream17) uses a school computer that blocks the CLA site. I did not mention this in commit comment above so CLA bot does not pick up the name and request the CLA again.
(cherry picked from commit a86d8545221b16e714ffe3bda5afafc1d4748d13)

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>