[documentation] Client node configured as server

[EugenKon]

Overview of the Issue

https://developer.hashicorp.com/consul/docs/agent#client-node-with-multiple-interfaces-or-ip-addresses

This is confusing that client node configured as server = true. Previous section does not have this:

[Abhinav-CHD]

Hey can I work on this issue?

[tysoncung]

Documentation improvements are always valuable! I'd be happy to help with this. What specific areas do you think need better documentation?