Faq stuff

Reviewing the FAQs threw up a few items which should be documented - https://trello.com/c/3uqvWhlq/240-faq-issues-needing-moved-to-docs-plone
This is the 1st PR in this effort towards ditching them completely, dealing with troubleshooting issues and ldap.

There is another card for ldap changes - https://trello.com/c/LerTrYZj/118-ldap-docs - which I am happy to also address if someone has time to give me pointers/stick the relevant info in a gdoc or similar.
Note: this line has changed in 5.1.