Add none model line to conf/agent.properties

Author: nvazquez

agent/conf/agent.properties

@@ -286,6 +286,7 @@ hypervisor.type=kvm
 
 # The model of Watchdog timer to present to the Guest.
 # For all models refer to the libvirt documentation.
+# PLEASE NOTE: to disable the watchdogs definitions, use value: none
 #vm.watchdog.model=i6300esb
 
 # Action to take when the Guest/Instance is no longer notifying the Watchdog timer.