Update README.md to highlight chatbot arena (#2596)

README.md

@@ -1,7 +1,11 @@
 # FastChat
 | [**Demo**](https://chat.lmsys.org/) | [**Discord**](https://discord.gg/HSWAKCrnFx) | [**X**](https://x.com/lmsysorg) |
 
-FastChat is an open platform for training, serving, and evaluating large language model based chatbots. The core features include:
+FastChat is an open platform for training, serving, and evaluating large language model based chatbots.
+- FastChat powers Chatbot Arena (https://chat.lmsys.org/), serving over 4 million chat requests for 30+ LLMs.
+- Arena has collected over 80K human votes from side-by-side LLM battles to compile an online [LLM Elo leaderboard](https://huggingface.co/spaces/lmsys/chatbot-arena-leaderboard).
+
+FastChat's core features include:
 - The training and evaluation code for state-of-the-art models (e.g., Vicuna, MT-Bench).
 - A distributed multi-model serving system with web UI and OpenAI-compatible RESTful APIs.