Bug 32644: Terminology: staff/intranet and biblio in plugins-home page

Bug 32644: Terminology: staff/intranet and biblio in plugins-home page

This patch replaces some incorrect terminology in the plugins-home page.
The current terminology is available at https://wiki.koha-community.org/wiki/Terminology

To test:
0. Make sure you have no enhanced content plugins installed
1. Apply patch
2. Go to Administration > Manage plugins
3. Click 'View plugins by class'
   --> Notice that one of the options is 'View bibliographic record enhancement
   plugins for the staff interface'
4. Make sure this phrase is gramatically correct, makes sense and has no
   typos
5. Click on that option
   --> Notice that the message says 'No plugins that can enhance the bibliographic
   records in the staff interface are installed'
6. Make sure this phrase is gramatically correct, makes sense and has no
   typos

Signed-off-by: Andrew Fuerste-Henry <andrewfh@dubcolib.org>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>