Move node.pause-on-idle setting to config files

So that we can configure it.
Add some more docs to the config file

src/daemon/media-session.d/v4l2-monitor.conf

@@ -38,7 +38,7 @@ rules = [
                 #node.nick = 			null
                 #priority.driver = 		100
                 #priority.session = 		100
-                #node.pause-on-idle = 		true
+                node.pause-on-idle = 		false
             }
         }
     }