docs: update readme for pip install ai-dynamo[trtllm] (#5312)

Signed-off-by: Anant Sharma <anants@nvidia.com>

README.md

@@ -259,9 +259,12 @@ sudo apt-get -y install libzmq3-dev
 ### After installing the pre-requisites above, install Dynamo
 
 ```
-uv pip install ai-dynamo[trtllm]
+pip install --pre --extra-index-url https://pypi.nvidia.com ai-dynamo[trtllm]
 ```
 
+> [!Note]
+> We use `pip` instead of `uv` here because `tensorrt-llm` has a URL-based git dependency (`etcd3`) that `uv` does not currently support.
+
 Run the backend/worker like this:
 
 ```