We need to document changes introduced by 

Bug 1416639 - Reject NFS storage configurations for registry, logging, metrics

for 3.9+ when this goes live and also need do highlight that this affects updates as well as outlined by 

https://bugzilla.redhat.com/show_bug.cgi?id=1416639#c14

As outlined by https://bugzilla.redhat.com/show_bug.cgi?id=1416639#c6 this kind of configuration is still supported but not recommended.

IMHO it would be best to highlight this in the upgrade section and move this kind of configuration out of advanced install to a separate section, so it is still documented but not in the advanced sections to avoid customers not reading the change or ignoring it still follow advanced config and have as a consequence install failed.