update readme

Author: jiweiqi

README.md

@@ -1,6 +1,10 @@
 # CRNN (Chemical Reaction Neural Network)
 
-The code will be avaliable upon the publish of Ji, Weiqi, and Sili Deng. "Autonomous Discovery of Unknown Reaction Pathways from Data by Chemical Reaction Neural Network." arXiv preprint arXiv:2002.09062 (2020). Currently, the code is avaliable upon request.
+![CRNN_TOC](./assets/CRNN_TOC.png)
+
+The code will be avaliable upon the publish of Ji, Weiqi, and Sili Deng. "Autonomous Discovery of Unknown Reaction Pathways from Data by Chemical Reaction Neural Network." arXiv preprint arXiv:2002.09062 (2020). 
+
+Currently, the code is avaliable upon request.
 
 # Cite
 Ji, Weiqi, and Sili Deng. "Autonomous Discovery of Unknown Reaction Pathways from Data by Chemical Reaction Neural Network." arXiv preprint arXiv:2002.09062 (2020).