[Feature request]: Document _x-puppet-fileserver

[bastelfreak]

Use Case

openvox agent supports three SRV lookups. For the server, the CA and the fileserver:
https://github.com/OpenVoxProject/openvox/blob/main/lib/puppet/http/dns.rb#L51-L55
I didn't find some documentation about _x-puppet-fileserver at https://docs.openvoxproject.org/

Describe the solution you would like

I'm really not sure when/how an external fileserver is used and I never used _x-puppet-fileserver before.

Describe alternatives you've considered

No response

Additional context

No response