add quantecon import for jax_intro

Author: mmcky

lectures/jax_intro.md

@@ -18,7 +18,7 @@ In addition to what's in Anaconda, this lecture will need the following librarie
 ```{code-cell} ipython3
 :tags: [hide-output]
 
-!pip install jax
+!pip install jax quantecon
 ```
 
 This lecture provides a short introduction to [Google JAX](https://github.com/google/jax).