Migrate docs from Sphinx to MkDocs (#18145)

Signed-off-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>

docs/deployment/frameworks/open-webui.md

@@ -0,0 +1,29 @@
+---
+title: Open WebUI
+---
+[](){ #deployment-open-webui }
+
+1. Install the [Docker](https://docs.docker.com/engine/install/)
+
+2. Start the vLLM server with the supported chat completion model, e.g.
+
+```console
+vllm serve qwen/Qwen1.5-0.5B-Chat
+```
+
+1. Start the [Open WebUI](https://github.com/open-webui/open-webui) docker container (replace the vllm serve host and vllm serve port):
+
+```console
+docker run -d -p 3000:8080 \
+--name open-webui \
+-v open-webui:/app/backend/data \
+-e OPENAI_API_BASE_URL=http://<vllm serve host>:<vllm serve port>/v1 \
+--restart always \
+ghcr.io/open-webui/open-webui:main
+```
+
+1. Open it in the browser: <http://open-webui-host:3000/>
+
+On the top of the web page, you can see the model `qwen/Qwen1.5-0.5B-Chat`.
+
+![](../../assets/deployment/open_webui.png)