Bug 7603: Change description of 952$3 in German frameworks to reflect new functionality

Bug 7603: Change description of 952$3 in German frameworks to reflect new functionality

952$a can be used for a note about accompanying materials. The note will now
show up on checkout, on return and on staff's catalog detail page.
Patch changes the field description in the German frameworks,
attempting to make it a bit more clear what the field can be used for.

To test:
Run the webinstaller selecting German and make sure all bibliographic
Frameworks (Default, Fast add, sample frameworks) install without errors.

Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>
I can't comment on the translations, but the installation seems to work.

Signed-off-by: Paul Poulain <paul.poulain@biblibre.com>