update diffphys intro

references.bib

@@ -863,3 +863,21 @@
   year={2014}
 }
 
+@article{silver2017mastering,
+  title={Mastering the game of {Go} without human knowledge},
+  author={Silver, David and Schrittwieser, Julian and Simonyan, Karen and Antonoglou, Ioannis and Huang, Aja and others},
+  journal={Nature},
+  volume={550},
+  number={7676},
+  year={2017}
+}
+
+@book{sutton2018rl,
+  title={Reinforcement learning: An introduction},
+  author={Sutton, Richard S and Barto, Andrew G},
+  year={2018},
+  publisher={MIT press}
+}
+
+
+