message: TF docs: Added note to `Dataset.prefetch` about interaction with batching.
diff: @@ -626,6 +626,9 @@ class DatasetV2(object):
  def prefetch(self, buffer_size):
  """Creates a `Dataset` that prefetches elements from this dataset.
  + Note that if the dataset was batched using `Dataset.batch`, each element is
  + a batch and this operation will prefetch `buffer_size` batches.
  +
  Args:
  buffer_size: A `tf.int64` scalar `tf.Tensor`, representing the
  maximum number of elements that will be buffered when prefetching.
  