Bug 31923: 'Ignore' tab description is misleading

Bug 31923: 'Ignore' tab description is misleading

This patch modifies the description of the 'Ignore' tab in
MARC bibliographic and authority framework administration
to add that not only does the 'ignored' subfield not appear
in the editor, but the subfield will also be deleted from the
record.

To test:
1. Go to Administration > MARC bibliographic framework
2. Click 'Actions' next to any framework and choose 'MARC structure'
3. Click 'Actions' next to any field and choose 'Edit subfields'
4. Check the hint/description under 'Managed in tab' and make sure it
   - makes sense
   - is written in correct english (syntax and spelling)
   - mentions that the subfield's value will be deleted from the record
5. Go to Administration > Authority types
6. Redo steps 2-4 for authority frameworks

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>