template: tweak to warning message

public/app/features/templating/editor_ctrl.ts

@@ -78,7 +78,7 @@ export class VariableEditorCtrl {
       }
 
       if ($scope.current.type === 'query' && $scope.current.query.match(new RegExp('\\$' + $scope.current.name))) {
-        $scope.appEvent('alert-warning', ['Validation', 'Query contains variable self-reference']);
+        $scope.appEvent('alert-warning', ['Validation', 'Query cannot contain a reference to itself. Variable: $'  + $scope.current.name]);
         return false;
       }