Rewrite docstring for OptimisticResponseTypeMixin

aleksis/core/schema/base.py

@@ -80,8 +80,14 @@ class PermissionsTypeMixin:
 class OptimisticResponseTypeMixin:
     """Mixin for using OptimisticResponse in the frontend.
 
-    Simply adds a field called `is_optimistic` that is always false,
-    but should be set to true by the frontend
+    In the frontend, Apollo can be configured to show an optimistic
+    response defined by the developer although the actual request
+    isn't yet finished. This way the frontend can directly update
+    and replace the optimistc data with the actual data from the
+    backend when the request is finished.
+
+    To know whether a response is optimistic or real, the field
+    `is_optimistic` can be set to true in the frontend.
     """
 
     is_optimistic = graphene.Boolean(default_value=False)