[bug-mailutils] mh program usage msg improvement

[djh]

I have a recommendation that should make
the mh program "rmm" easier to understand for people
new to MH.

Neither the :  rmm --usage or rmm -help mention the "all" option for
specifying which messages to delete.  I recommend  changing the

[msgs]  in these print statements to -->   [msgs | "all"]   or to  [msgs | all]

For example. the new outputs would be something like.
$ rmm --help
Usage: rmm [OPTION...] [+folder] [msgs | "all"]

---- and
$ rmm --usage
Usage: rmm [-?V] [--folder=FOLDER] [--help] [--license] [--usage] [--version]
           [+folder] [msgs | "all"]

---

This is a trivial change, but helpful to people and provides more
accurate help/usage statements.

Regards,
  Darel Henman

P.S.
movemail "file:///var/spool/mail/djh"  "mh://$MHMAIL/inbox"

successfully moved messages from a unix mbox format to mh format
files, on this cygwin platform.