message: Updated linear activation function with arguments, returns and note.
diff: @@ -198,6 +198,17 @@ def hard_sigmoid(x):
  @keras_export('keras.activations.linear')
  def linear(x):
  + """Linear activation function.
  +
  + Arguments:
  + x: Input tensor.
  +
  + Returns:
  + Linear activation:
  +
  + # Note
  + - Often used as last layer of regression networks.
  + """
  return x
  