Bug 19000: Fix typo in closing p tag for items

Bug 19000: Fix typo in closing p tag for items

Close the p tag and add a br tag to visually divide the two sections
Data problems and Warnings regarding system configuration.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Discovered the problem when testing a duplicate key in deleteditems.

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit 3c87b6f387831053e01ecc86b91d61669af9696b)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>