README: mistake in formulation of firewall rule

I believe that

`sudo ufw allow from <your-mobile-device's-LAN-static-ip> to any port <your-config-port>`

should be

`sudo ufw allow from <your-mobile-device's-LAN-static-ip> to <your-server-device's-LAN-static-ip> port <your-config-port>`

If I am wrong about that, then I submit that the firewalling instructions could be clearer.