Add Jax compilation more prominently to README (#4380)

* Add Jax compilation more prominently

* Update README.rst

Co-authored-by: Thomas Wiecki <[email protected]>

Author: canyon289

README.rst

@@ -39,8 +39,8 @@ Features
 -  **Variational inference**: `ADVI <http://www.jmlr.org/papers/v18/16-107.html>`__
    for fast approximate posterior estimation as well as mini-batch ADVI
    for large data sets.
--  Relies on `Theano <https://theano-pymc.readthedocs.io/en/latest/>`__ which provides:
-    *  Computation optimization and dynamic C compilation
+-  Relies on `Theano-PyMC <https://theano-pymc.readthedocs.io/en/latest/>`__ which provides:
+    *  Computation optimization and dynamic C or JAX compilation
     *  Numpy broadcasting and advanced indexing
     *  Linear algebra operators
     *  Simple extensibility