Bug 24838: Fix help link for patron categories

Bug 24838: Fix help link for patron categories

To test:
- go to admin/categories.pl
- click Help, confirm it takes you to manual main page
- apply patch
- restart all
- click Help, confirm it takes you to patron categories in manual

Signed-off-by: Sally <sally.healey@cheshiresharedservices.gov.uk>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Joy Nelson <joy@bywatersolutions.com>
(cherry picked from commit 5fbde57bbcb5c4035c6e7a5a7416ebbc407719e2)

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>