Change feeding comments.

python/paddle/v2/data_feeder.py

@@ -39,9 +39,8 @@ class DataFeeder(DataProviderConverter):
 
     ..  code-block:: python
 
-        data_types = [('image', paddle.data_type.dense_vector(784)),
-                      ('label', paddle.data_type.integer_value(10))]
         feeding = ['image', 'label']
+        data_types = enumerate_data_types_of_data_layers(topology)
         feeder = DataFeeder(data_types=data_types, feeding=feeding)
 
         minibatch_data = [([1.0, 2.0, 3.0, ...], 5)]

python/paddle/v2/trainer.py

@@ -81,7 +81,7 @@ class SGD(object):
         :type event_handler: (BaseEvent) => None
         :param feeding: Feeding is a map of neural network input name and array
                         index that reader returns.
-        :type feeding: dict
+        :type feeding: dict|list
         :return:
         """
         if event_handler is None: