fix: nixd option groups and documentation page (#4594) #5448

Job	Run time
test (ubuntu-latest, 27.2, false)	2m 4s
test (ubuntu-latest, 28.2, false)	2m 28s
test (ubuntu-latest, 29.4, false)	2m 38s
test (macos-latest, 28.2, false)	3m 48s
test (macos-latest, 29.4, false)	4m 2s
test (windows-latest, 27.2, false)	3m 51s
test (windows-latest, 28.2, false)	4m 21s
test (windows-latest, 29.4, false)	3m 9s
test (ubuntu-latest, snapshot, true)	1m 28s
test (macos-latest, snapshot, true)	3m 6s
test (windows-latest, snapshot, true)	5m 4s
	35m 59s

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