Update output-data-providers.md

docs/guide/output-data-providers.md

@@ -34,6 +34,7 @@ And the following example shows how to use ActiveDataProvider without ActiveReco
 $query = new Query();
 $provider = new ActiveDataProvider([
     'query' => $query->from('post'),
+    'sort'=>['defaultOrder'=>['name' => SORT_ASC,'created_at' => SORT_DESC]],
     'pagination' => [
         'pageSize' => 20,
     ],