message: [tf.data] correction in document.
diff: @@ -2147,8 +2147,8 @@ class StructuredFunctionWrapper(object):
  default graph.
  use_legacy_function: (Optional.) A boolean that determines whether the
  function be created using `tensorflow.python.eager.function.defun`
  - (default behavior) or `tensorflow.python.eager.function.Defun` (legacy
  - beheavior).
  + (default behavior) or `tensorflow.python.framework.function.Defun`
  + (legacy beheavior).
  defun_kwargs: (Optional.) A dictionary mapping string argument names to
  values. If supplied, will be passed to `function` as keyword arguments.
  