Hidden commands not in the manual

[Eli Zaretskii]

lookup-revision and revision-info are not in the manual (at least not
on Windows) in bzr 2.3.1, but "bzr help" does know about them.

I see that these are "hidden" commands.  Is there a reason for them to
be hidden?

More generally, should hidden command appear in the manual, at least
in a separate section?  Having them in the manual would make it easier
to find them when they are needed.

TIA