Previously the docs for this were rather confusing because they showed an
option to turn _on_ state locking, even though it's on by default.
Instead, we'll now show -lock=false in all cases and document it as
_disabling_ the default locking.
While working on this I also noticed that the equivalent docs on the
website were differently inconsistent. I've not made them fully consistent
here but at least moreso than they were before.
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