lib.wiring: fix Signature.is_compliant docstring #3541

Job	Run time
document	49s
smoke (amaranth-lang/amaranth-boards)	31s
smoke (amaranth-lang/amaranth-stdio)	36s
test (3.8)	2m 17s
smoke (amaranth-lang/amaranth-soc)	42s
test (3.9)	2m 16s
test (3.10)	2m 24s
test (3.11)	2m 36s
test (3.12)	4m 5s
test (pypy-3.8)	5m 11s
check-links	56s
test (pypy-3.9)	5m 50s
test (pypy-3.10)	4m 43s
test (3.13-dev)	3m 12s
publish-docs	5s
publish-docs-dev	0s
required	1s
publish-package	39s
publish-schemas	6s
publish-release	0s
	36m 59s

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