message: Fix incorrect doc in tf.layers.dense
  This fix tries to address the issue raised in 21525 where
  the doc in tf.layers.dense is not correct. Specifically
  `outputs = activation(inputs.kernel + bias) Where` ->
  `outputs = activation(inputs * kernel + bias) where`
  This fix fixes 21525.
diff: @@ -127,8 +127,8 @@ def dense(
  """Functional interface for the densely-connected layer.
  This layer implements the operation:
  - `outputs = activation(inputs.kernel + bias)`
  - Where `activation` is the activation function passed as the `activation`
  + `outputs = activation(inputs * kernel + bias)`
  + where `activation` is the activation function passed as the `activation`
  argument (if not `None`), `kernel` is a weights matrix created by the layer,
  and `bias` is a bias vector created by the layer
  (only if `use_bias` is `True`).
  