Update README with module 2 description.

Author: gillsignals

README.md

@@ -4,3 +4,7 @@ Repository for code used in JHU EN.580.430 - Systems Pharmacology, Spring 2022
 ## `module1_pk`: Code for module 1 on pharmacokinetics and ODEs
 
 To run these models, clone this repo and navigate in Matlab to the folder with your model of choice. Open the `*_main.m` file or the `*_driver.m` file and hit "Run". You do not need to run the `*_eqns.m` file - this will automatically be called, along with any other needed files in the same directory, when the main/driver file is run.
+
+## `module2_pop_pk`: Code for module 2 on population pharmacokinetics
+
+To run these models, open the folder with the model of your choice and run the `*_driver.m` file in Matlab. Other files will automatically be called inside of this driver.