Apache frontend: Explain parameters.

software/apache-frontend/README.apache_frontend.txt

@@ -117,3 +117,6 @@ not run as root. It is a good idea then to go on the node where the instance is
 and set some iptables rules like (if using default ports)::
   iptables -t nat -A PREROUTING -p tcp -d {public ip} --dport 443 -j DNAT --to-destination {listening ip}:4443
   iptables -t nat -A PREROUTING -p tcp -d {public_ip} --dport 80 -j DNAT --to-destination {listening ip}:8080
+
+Where {public ip} is the public IP of your server, or at least the LAN IP to where your NAT will forward to.
+{listening ip} is the private ipv4 (like 10.0.34.123) that the instance is using and sending as connection parameter.