modules UPDATE uncomment notification container

It casued problems in the past because it caused
operational data validation to fail because of
its mandatory leaf. With custom lenient operational
validation it is no longer the case.

Fixes #1536

modules/notifications@2008-07-14.yang

@@ -80,7 +80,7 @@ module notifications {
       }
     }
 
-   /*container notification {
+   container notification {
       description "internal struct to start a notification";
       config false;
 
@@ -90,6 +90,6 @@ module notifications {
       }
 
       // eventType and any data content goes here
-   }*/
+   }
 }