Documented parameters of callbacks

Author: edenhill

docs/index.rst

@@ -78,14 +78,14 @@ The Python bindings also provide some additional configuration properties:
 * ``default.topic.config``: value is a dict of topic-level configuration
   properties that are applied to all used topics for the instance.
 
-* ``error_cb``: Callback for generic/global error events. This callback is served by
+* ``error_cb(kafka.KafkaError)``: Callback for generic/global error events. This callback is served by
   poll().
 
-* ``on_delivery`` (**Producer**): value is a Python function reference
+* ``on_delivery(kafka.KafkaError, kafka.Message)`` (**Producer**): value is a Python function reference
   that is called once for each produced message to indicate the final
   delivery result (success or failure).
   This property may also be set per-message by passing ``callback=callable``
   (or ``on_delivery=callable``) to the confluent_kafka.Producer.produce() function.
 
-* ``on_commit`` (**Consumer**): Callback used to indicate success or failure
+* ``on_commit(kafka.KafkaError, list(kafka.TopicPartition))`` (**Consumer**): Callback used to indicate success or failure
   of commit requests.