Bug 17266 - Update man page for koha-remove with -p

Bug 17266 - Update man page for koha-remove with -p

Bug 9754 added the -p|--purge-all option to koha-remove, but this
was not documented in the man page. This patch fixes that.

To test:
Run these commands and look at the formatted man page:
$ xsltproc /usr/share/xml/docbook/stylesheet/docbook-xsl/manpages/docbook.xsl \
  debian/docs/koha-remove.xml
$ man -l koha-remove.8

Make sure this test passes:
$ prove -v xt/verify-debian-docbook.t

Signed-off-by: Liz Rea <liz@catalyst.net.nz>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>