Add comment clarifying items in predictions list

This way, it becomes clear what the result of the `print()` call will look like.

tensorflow/contrib/distribute/python/examples/simple_estimator_example.py

@@ -79,6 +79,8 @@ def main(_):
     return predict_features
 
   prediction_iterable = estimator.predict(input_fn=predict_input_fn)
+  # Create a list containing each of the prediction dictionaries that map 
+  # the key 'logits' to an array of model outputs.
   predictions = [prediction_iterable.next() for _ in range(10)]
   print("Prediction results: {}".format(predictions))