message: Fix typo in docstring for custom_gradient.
diff: @@ -100,8 +100,8 @@ def custom_gradient(f=None):
  return tf.math.log(1 + tf.exp(x))
  ```
  - Due to numerical instability, the gradient this function evaluated at x=100 is
  - NaN. For example:
  + Due to numerical instability, the gradient of this function evaluated at x=100
  + is NaN. For example:
  ```python
  x = tf.constant(100.)
  