Update godoc for newServer to reflect DNS and IP-based inputs

Requested by: alex

client/rpcproxy/server_endpoint.go

@@ -40,7 +40,11 @@ func (s *ServerEndpoint) Key() *EndpointKey {
 	}
 }
 
-// newServer creates a new Server instance with a resolvable endpoint
+// newServer creates a new Server instance with a resolvable endpoint.
+// `name` can be either an IP address or a DNS name.  If `name` is a DNS
+// name, it must be resolvable to an IP address (most inputs are IP
+// addresses, not DNS names, but both work equally well when the name is
+// resolvable).
 func newServer(name string) (s *ServerEndpoint, err error) {
 	s = &ServerEndpoint{
 		Name: name,