Add note to docs about unsaved files #11783

Job	Run time
spelling	12s
lint_node	26s
build_node (ubuntu-latest)	1m 27s
Ruby 3.1 on ubuntu-latest	16m 55s
lint_ruby	26s
build_node (macos-latest)	1m 33s
Ruby 3.2 on ubuntu-latest	15m 52s
build_node (windows-latest)	7m 5s
Verify Jekyll website builds	9s
Ruby 3.3 on ubuntu-latest	12m 19s
Ruby 3.1 on macos-latest	12m 34s
Ruby 3.2 on macos-latest	9m 30s
Ruby 3.3 on macos-latest	11m 8s
Ruby 3.1 on windows-latest	22m 20s
Ruby 3.2 on windows-latest	28m 13s
Ruby 3.3 on windows-latest	23m 43s
	2h 43m 52s

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