Fix minor typo in cell (#2692)
Fix minor typo in cell (#2692)

* Fix minor typo in cell

One of the arguments to `hvp` wasn't being used, which made the example slightly confusing.

* Fix both definitions of hvp in the autodiff cookbook.

Co-authored-by: Peter Hawkins <34b19541630131950b5f204f2c5f2c647a3a7475@google.com>
google/jax,google/jax,tensorflow/probability,google/jax,google/jax,tensorflow/probability