Update _index.md

Adding "Serve models on OpenAI-compatible APIs for easy integration with existing apps" to the list of key features as I think this needs to be front and center when talking about DMR.

Author: nigelpoulton

content/manuals/ai/model-runner/_index.md

@@ -19,6 +19,7 @@ aliases:
 ## Key features
 
 - [Pull and push models to and from Docker Hub](https://hub.docker.com/u/ai)
+- Serve models on OpenAI-compatible APIs for easy integration with existing apps
 - Package GGUF files as OCI Artifacts and publish them to any Container Registry
 - Run and interact with AI models directly from the command line or from the Docker Desktop GUI
 - Manage local models and display logs