fix issue w/ tags binding

apps/search_indexes/documents/tag_category.py

@@ -32,3 +32,11 @@ class TagCategoryDocument(Document):
 
     def get_queryset(self):
         return super().get_queryset().with_base_related()
+
+    def get_instances_from_related(self, related_instance):
+        """If related_models is set, define how to retrieve the Car instance(s) from the related model.
+        The related_models option should be used with caution because it can lead in the index
+        to the updating of a lot of items.
+        """
+        if isinstance(related_instance, News):
+            return related_instance.tags