message: Update `Note` section of Dense layer doc to clarify about the matmul behavior when input rank > 2.
diff: @@ -1031,8 +1031,15 @@ class Dense(Layer):
  created by the layer, and `bias` is a bias vector created by the layer
  (only applicable if `use_bias` is `True`).
  - Note: If the input to the layer has a rank greater than 2, then
  - it is flattened prior to the initial dot product with `kernel`.
  + Note: If the input to the layer has a rank greater than 2, then `Dense`
  + computes the dot product between the `inputs` and the `kernel` along the
  + last axis of the `inputs` and axis 1 of the `kernel` (using `tf.tensordot`).
  + For example, if input has dimensions `(batch_size, d0, d1)`,
  + then we create a `kernel` with shape `(d1, units)`, and the `kernel` operates
  + along axis 2 of the `input`, on every sub-tensor of shape `(1, 1, d1)`
  + (there are `batch_size * d0` such sub-tensors).
  + The output in this case will have shape `(batch_size, d0, units)`.
  +
  Besides, layer attributes cannot be modified after the layer has been called
  once (except the `trainable` attribute).
  