message: Fix NumPy equivalent comment.
diff: @@ -857,7 +857,7 @@ def stack(values, axis=0, name="stack"):
  This is the opposite of unstack. The numpy equivalent is
  ```python
  - tf.stack([x, y, z]) = np.asarray([x, y, z])
  + tf.stack([x, y, z]) = np.stack([x, y, z])
  ```
  Args:
  @@ -997,7 +997,7 @@ def unstack(value, num=None, axis=0, name="unstack"):
  This is the opposite of stack. The numpy equivalent is
  - tf.unstack(x, n) = list(x)
  + tf.unstack(x, n) = np.unstack(x)
  Args:
  value: A rank `R > 0` `Tensor` to be unstacked.
  