gendocs.sh: license statement

[Simon Josefsson]

I based a script on gendocs.sh, and while copying the text, I happened
to read what --version said:

 There is NO warranty.  You may redistribute this software
 under the terms of the GNU General Public License.
 For more information about these matters, see the files named COPYING.

The plural of 'files' sounded weird to me, but english isn't my mother
tongue.  I wouldn't have mentioned this if I hadn't also noticed that
the origin of the blurb appear to be the GNU Standards manual:

          You may redistribute copies of GNU Emacs
          under the terms of the GNU General Public License.
          For more information about these matters,
          see the files named COPYING.

Should 'files' be 'file'?  Examples from standards.texi is likely to
get cut'n'pasted a lot, so might be good to fix.  If it is
intentional, I'm always happy to improve my understanding of
english...

Thanks,
Simon