message: Update `Flatten` layer docs.
diff: @@ -598,8 +598,8 @@ class Permute(Layer):
  class Flatten(Layer):
  """Flattens the input. Does not affect the batch size.
  - If inputs are shaped `(batch,)` without a channel dimension, then flattening
  - adds an extra channel dimension and output shapes are `(batch, 1)`.
  + Note: If inputs are shaped `(batch,)` without a feature axis, then
  + flattening adds an extra channel dimension and output shape is `(batch, 1)`.
  Arguments:
  data_format: A string,
  @@ -614,16 +614,15 @@ class Flatten(Layer):
  Example:
  - ```python
  - model = Sequential()
  - model.add(Convolution2D(64, 3, 3,
  - border_mode='same',
  - input_shape=(3, 32, 32)))
  - # now: model.output_shape == (None, 64, 32, 32)
  + >>> model = tf.keras.Sequential()
  + >>> model.add(tf.keras.layers.Conv2D(64, 3, 3, input_shape=(3, 32, 32)))
  + >>> model.output_shape
  + (None, 1, 10, 64)
  +
  + >>> model.add(Flatten())
  + >>> model.output_shape
  + (None, 640)
  - model.add(Flatten())
  - # now: model.output_shape == (None, 65536)
  - ```
  """
  def __init__(self, data_format=None, **kwargs):
  