Bug 14391: (QA follow-up) Resolve POD warn on svc..systempreferences

Bug 14391: (QA follow-up) Resolve POD warn on svc..systempreferences

*** WARNING: No items in =over (at line 48) / =back list at line 54 in file svc/config/systempreferences
*** WARNING: No items in =over (at line 73) / =back list at line 79 in file svc/config/systempreferences

=> If you use 'over', you should add 'item'-s.

Test plan:
Run perldoc svc/config/systempreferences

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>