[PATCH] Update the help doc of svnversion

Hi,

  In r877617, Arfrever improved some messages printed by svnversion
while invoking it on unversioned files and directories.
Updating the same in help doc also.

Herewith attached a patch that updates the help doc string of svnversion
program.

[[[
When svnversion is called on a directory/file that is not versioned, the
output message would be
'Unversioned directory/file', as a result of r877617. Update the same in
help doc.

* subversion/svnversion/main.c
    help(): Update the doc string.

Patch by: Vijayaguru G <vijay_at_collab.net>

]]]

Thanks & Regards,
Vijayaguru