doc: Add link to listen_addresses as cause of connection failure

Reported-by: k.man.113@gmail.com

Discussion: https://postgr.es/m/171494070007.703.17021965362263796980@wrigleys.postgresql.org

Backpatch-through: master

Author: bmomjian

doc/src/sgml/runtime.sgml

@@ -637,7 +637,8 @@ psql: error: connection to server at "server.joe.com" (123.123.123.123), port 54
      This is the generic <quote>I couldn't find a server to talk
      to</quote> failure. It looks like the above when TCP/IP
      communication is attempted. A common mistake is to forget to
-     configure the server to allow TCP/IP connections.
+     configure <xref linkend="guc-listen-addresses"/> so that the server
+     accepts remote TCP connections.
     </para>
 
     <para>