mypy

typo fixes in docs (#142683) #18500

Job	Run time
Run mypy on Tools/cases_generator	15s
Run mypy on Tools/clinic	18s
Run mypy on Tools/jit	17s
Run mypy on Lib/test/libregrtest	20s
Run mypy on Tools/peg_generator	20s
Run mypy on Tools/build	17s
Run mypy on Lib/_pyrepl	24s
Run mypy on Lib/tomllib	17s
	2m 28s

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