Quick install into existing server clarification regarding names wanted

It would be useful to clarify the Set the FQDN section of the jitsi-meet quick install for the case where you want to install Jitsi on an existing server - myserver.example.org, which could already have CNAMES for service1.example.org etc.

I can see that adding meet.example.org to the loopback address in /etc/hosts allows Jitsi components to connect, presumably, to prosody on localhost etc as meet.example.org via loopback rather than the external IP discovered via DNS, but not sure what the function of changing the hostnane ? - particularly as this could already be tied into - for example - system backups - maybe even as something completely different - such as hosted1234.example.com