docs: Fix simple typo, attibutes -> attributes

There is a small typo in rest_framework_docs/api_endpoint.py.

Should read `attributes` rather than `attibutes`.

Author: timgates42

Diff for: rest_framework_docs/api_endpoint.py

@@ -125,7 +125,7 @@ def __get_serializer_fields__(self, serializer):
                     "to_many_relation": to_many_relation
                 })
             # FIXME:
-            # Show more attibutes of `field`?
+            # Show more attributes of `field`?
 
         return fields