Bug 25576: Add link to the manual for the ILL module

Bug 25576: Add link to the manual for the ILL module

Test plan:
Enable ILLModule system preference.
Go to ILL requests
Click Help

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit 50b6e447735ee31a2fbba5b116959cdb6d451c19)

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
(cherry picked from commit abc259607eb9b0a8e9781e29c664fecfce103ac2)

Signed-off-by: Aleisha Amohia <aleishaamohia@hotmail.com>