Bug 13686 Add a hint about collation to the alphabet syspref

Bug 13686 Add a hint about collation to the alphabet syspref

New attempt from a fresh branch.

Test plan:
* Look at the alphabet syspref.
* Install the patch.
* Look again at the alphabet syspref and you should see a short hint about collation.

Thanks for the patience - I already learned a few new things about Git with this patch.

Text appears as expected.
Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Amended patch: add a br tag

Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>