perm.texi from coreutils

[Aaron S. Hawley]

A documentation patch that I sent to the coreutils folks about a few typos
in perm.texi was applied last month.  findutils could update its
"Permissions" section of the file by getting the latest version from them.

- Findutils version:
<http://savannah.gnu.org/cgi-bin/viewcvs/findutils/findutils/doc/perm.texi>
- Coreutils version:
<http://savannah.gnu.org/cgi-bin/viewcvs/coreutils/coreutils/doc/perm.texi>

It's been 5 years since an update.

I am willing to volunteer to look into precisely what merges would be
necessary to take their changes.
/a