Update README.md (#2492)

Author: merrymercy

README.md

@@ -6,12 +6,12 @@ FastChat is an open platform for training, serving, and evaluating large languag
 - A distributed multi-model serving system with web UI and OpenAI-compatible RESTful APIs.
 
 ## News
-- [2023/08] 🔥 We released **Vicuna v1.5** based on Llama 2 with 4K and 16K context lengths. Download [weights](#vicuna-weights).
-- [2023/08] 🔥 We released **LongChat v1.5** based on Llama 2 with 32K context lengths. Download [weights](#longchat).
+- [2023/09] 🔥 We released **LMSYS-Chat-1M**, a large-scale real-world LLM conversation dataset. Read the [report](https://arxiv.org/abs/2309.11998).
+- [2023/08] We released **Vicuna v1.5** based on Llama 2 with 4K and 16K context lengths. Download [weights](#vicuna-weights).
 - [2023/07] We released **Chatbot Arena Conversations**, a dataset containing 33k conversations with human preferences. Download it [here](https://huggingface.co/datasets/lmsys/chatbot_arena_conversations).
 
 <details><summary>More</summary>
-
+- [2023/08] We released **LongChat v1.5** based on Llama 2 with 32K context lengths. Download [weights](#longchat).
 - [2023/06] We introduced **MT-bench**, a challenging multi-turn question set for evaluating chatbots. Check out the blog [post](https://lmsys.org/blog/2023-06-22-leaderboard/).
 - [2023/06] We introduced **LongChat**, our long-context chatbots and evaluation tools. Check out the blog [post](https://lmsys.org/blog/2023-06-29-longchat/).
 - [2023/05] We introduced **Chatbot Arena** for battles among LLMs. Check out the blog [post](https://lmsys.org/blog/2023-05-03-arena).