Fix indent in a docstring #16907

Job	Run time
doctest (1.10, ubuntu-latest)	25m 36s
doctest (1.11-nightly, ubuntu-latest)	25m 46s
test (1.6, short, ubuntu-latest)	1h 40m 17s
doctest (nightly, ubuntu-latest)	30m 59s
test (1.6, long, ubuntu-latest)	56m 21s
doctest (1.10, ubuntu-latest, depwarn=error)	26m 9s
test (1.10, short, ubuntu-latest)	1h 13m 5s
doctest (1.10, macOS, RPTU)	12m 38s
test (1.10, long, ubuntu-latest)	44m 34s
test (1.11-nightly, short, ubuntu-latest)	1h 26m 38s
test (1.11-nightly, long, ubuntu-latest)	52m 2s
test (nightly, short, ubuntu-latest)	1h 21m 36s
test (nightly, long, ubuntu-latest)	50m 38s
test (1.10, short, ubuntu-latest, depwarn=error)	1h 10m 8s
test (1.10, long, ubuntu-latest, depwarn=error)	45m 24s
test (1.10, short, macOS, RPTU)	14m 15s
test (1.10, long, macOS, RPTU)	14m 16s
test (1.10, book, ubuntu-latest)	50m 29s
test (nightly, book, ubuntu-latest)	2h 30m 18s
	16h 51m 9s

Provide feedback