message: [core API doc fixit] tf.cast; explicitly mention the alias in the example.
  Aliases are only visible when user clicks on "+" sign on the API doc page. (https://www.tensorflow.org/api_docs/python/tf/cast#expandable-1) Using alias in the example can create confusion. Explicitly mention that the example uses the alias.
diff: @@ -915,6 +915,12 @@ def cast(x, dtype, name=None):
  For example:
  + >>> x = tf.constant([1.8, 2.2], dtype=tf.float32)
  + >>> tf.cast(x, tf.int32)
  + <tf.Tensor: shape=(2,), dtype=int32, numpy=array([1, 2], dtype=int32)>
  +
  + Notice `tf.cast` has an alias `tf.dtypes.cast`:
  +
  >>> x = tf.constant([1.8, 2.2], dtype=tf.float32)
  >>> tf.dtypes.cast(x, tf.int32)
  <tf.Tensor: shape=(2,), dtype=int32, numpy=array([1, 2], dtype=int32)>
  