Adding project publication using highway-env

Good afternoon, I used highway-env as the base code for my recent work on adversarial policy learning and wanted to add it in here!

README.md

@@ -224,6 +224,7 @@ List of publications & preprints using `highway-env` (please open a pull request
 *   [Explaining a Deep Reinforcement Learning (DRL)-Based Automated Driving Agent in Highway Simulations](https://ieeexplore.ieee.org/document/10077125) (Mar 2023)
 *   [Investigating High-Level Decision Making for Automated Driving](https://link.springer.com/chapter/10.1007/978-3-031-30333-3_41) (Apr 2023)
 *   [Implementing Deep Reinforcement Learning (DRL)-based Driving Styles for Non-Player Vehicles](https://journal.seriousgamessociety.org/index.php/IJSG/article/view/638) (Nov 2023)
+*   [Investigating Adversarial Policy Learning for Robust Agents in Automated Driving Highway Simulations](https://link.springer.com/chapter/10.1007/978-3-031-48121-5_18) (Jan 2024)
 
 PhD theses
 *   [Reinforcement learning for Dialogue Systems optimization with user adaptation](https://hal.inria.fr/tel-02422691/) (2019)