Fix some typos in help messages and command doco (#280) #1032

Job	Run time
test (ubuntu-latest, 26.3, false)	29s
test (ubuntu-latest, 27.2, false)	29s
test (ubuntu-latest, 28.2, false)	28s
test (ubuntu-latest, 29.4, false)	47s
test (macos-latest, 28.2, false)	1m 7s
test (macos-latest, 29.4, false)	1m 51s
test (windows-latest, 26.3, false)	3m 0s
test (windows-latest, 27.2, false)	1m 15s
test (windows-latest, 28.2, false)	1m 50s
test (windows-latest, 29.4, false)	1m 8s
test (ubuntu-latest, snapshot, true)	26s
test (macos-latest, snapshot, true)	1m 4s
test (windows-latest, snapshot, true)	3m 35s
	17m 29s

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