Bug 16165 - Include link to ILS-DI documentation page in ILS-DI system preference

Bug 16165 - Include link to ILS-DI documentation page in ILS-DI system preference

There is no clue in the system preference about the nice ILS-DI documentation
once you turn it on. We should include a note and the link, similar to how we
do it for the web self checkout.

Test plan:
Syspreference ILS-DI should now include URL in description.

Signed-off-by: Mirko Tietgen <mirko@abunchofthings.net>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit 9066ae153b15ae49b7d5832b331eed31c32ed583)
Signed-off-by: Frédéric Demians <f.demians@tamil.fr>