Bug 29004: Update GoogleOpenIDConnect preference to make it clear that it is OPAC...

Bug 29004: Update GoogleOpenIDConnect preference to make it clear that it is OPAC-only

This patch modifies the description of the GoogleOpenIDConnect and
related preferences to make it clear that GoogleOpenIDConnect affects
OPAC logins and that the preferences are related.

To test, apply the patch and go to Administration -> System preferences.

Search for "google," and confirm that the descriptions of
GoogleOpenIDConnect and related preferences look clear and correct.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>