message: Fixing doctest errors
diff: @@ -205,9 +205,7 @@ def custom_gradient(f=None):
  dtype=float32,
  numpy=array([1., 1., 1.], dtype=float32)>
  >>> tape.gradient(poly, weights)
  - <tf.Tensor: shape=(2,),
  - dtype=float32,
  - numpy=array([6., 3.], dtype=float32)>
  + <tf.Tensor: shape=(2,), dtype=float32, numpy=array([6., 3.], dtype=float32)>
  ```
  Above example illustrates usage of trainable variable `weights`.
  