Use SGLang main branch for Cosmos3 install

README.md

@@ -416,10 +416,10 @@ python scripts/upsample_prompt.py \
 
 ### SGLang
 
-SGLang-Diffusion can serve `nvidia/Cosmos3-Super-Image2Video` through the OpenAI-compatible async video endpoint. Install SGLang from source with diffusion dependencies, then start the server:
+SGLang-Diffusion can serve `nvidia/Cosmos3-Super-Image2Video` through the OpenAI-compatible async video endpoint. Install SGLang from the main branch with diffusion dependencies, then start the server:
 
 ```bash
-git clone https://github.com/sgl-project/sglang.git
+git clone --branch main https://github.com/sgl-project/sglang.git
 cd sglang
 pip install -e "python[diffusion]"
 pip install "cosmos-guardrail==0.3.1"
@@ -429,6 +429,8 @@ sglang serve \
   --num-gpus 4
 ```
 
+Cosmos 3 support in SGLang Diffusion currently requires the SGLang main branch. Switch to a stable SGLang release once Cosmos 3 support is included there.
+
 Example image-to-video request:
 
 ```bash