message: Update docstring regarding default behavior to match underlying function `save.save_model`.
diff: @@ -965,8 +965,8 @@ class Network(base_layer.Layer):
  target location, or provide the user with a manual prompt.
  include_optimizer: If True, save optimizer's state together.
  save_format: Either 'tf' or 'h5', indicating whether to save the model
  - to Tensorflow SavedModel or HDF5. The default is currently 'h5', but
  - will switch to 'tf' in TensorFlow 2.0.
  + to Tensorflow SavedModel or HDF5. Defaults to 'tf' in TF 2.X, and
  + 'h5' in TF 1.X.
  signatures: Signatures to save with the SavedModel. Applicable to the
  'tf' format only. Please see the `signatures` argument in
  `tf.saved_model.save` for details.
  