LLM4AAMAS: minor modification

README.md

@@ -208,7 +208,7 @@ Many models are available at the following URLs:
   Chenyan Jia, Ge Zhang, Denny Zhou, Andrew M. Dai, Diyi Yang, Soroush Vosoughi
   (2023)* Published on *arXiv* arXiv:2305.16960
 
-- [S3: Social-network Simulation System with Large Language Model-Empowered
+- **[S3: Social-network Simulation System with Large Language Model-Empowered
   Agents](https://arxiv.org/abs/2307.14984)** *Chen Gao, Xiaochong Lan, Zhihong
   Lu, Jinzhu Mao, Jinghua Piao, Huandong Wang, Depeng Jin, Yong Li (2023)*
   Published on *arXiv* arXiv:2307.14984