docs(guide/Components): add missing $ctrl

docs/content/guide/component.ngdoc

@@ -133,7 +133,7 @@ components should follow a few simple conventions:
     For a deletion, that means the component doesn't delete the `hero` itself, but sends it back to
     the owner component via the correct event.
     ```html
-        <button ng-click="$ctrl.onDelete({hero: hero})">Delete</button>
+        <button ng-click="$ctrl.onDelete({hero: $ctrl.hero})">Delete</button>
     ```
   - That way, the parent component can decide what to do with the event (e.g. delete an item or update the properties)
     ```js