Bug 8568 - Fix some errors in docs for scripts provided by the Debian packages

Bug 8568 - Fix some errors in docs for scripts provided by the Debian packages

1. Create a page for koha-run-backups
2. Fix the synopsis for koha-foreach
3. Add koha-create and koha-run-backups to koha-common

To test
- Convert the changed xml files to man pages with
$ xsltproc /usr/share/xml/docbook/stylesheet/docbook-xsl/manpages/docbook.xsl koha-x.xml
- View generated pages with e.g.
$ man -l koha-x.8"
  (Replace x with the names of the changed files)
- Check that the changes make sense

Signed-off-by: Frédéric Demians <f.demians@tamil.fr>
Works as described. I was able to produce the 3 man files, load them with man
command, and see the added information properly formated.

Signed-off-by: Paul Poulain <paul.poulain@biblibre.com>