docs: update README with nightly build instructions for mcp@next (#438)

Update readme to show how to use nightly builds

## GitHub issue number
N/A

## **Associated Risks**

None

## ✅ **PR Checklist**

- [x] **I have read the [contribution
guidelines](https://github.com/microsoft/azure-devops-mcp/blob/main/CONTRIBUTING.md)**
- [x] **I have read the [code of conduct
guidelines](https://github.com/microsoft/azure-devops-mcp/blob/main/CODE_OF_CONDUCT.md)**
- [x] Title of the pull request is clear and informative.
- [x] 👌 Code hygiene
- [x] 🔭 Telemetry added, updated, or N/A
- [x] 📄 Documentation added, updated, or N/A
- [x] 🛡️ Automated tests added, or N/A

## 🧪 **How did you test it?**

manual review

Author: danhellem

README.md

@@ -214,6 +214,27 @@ In your project, add a `.vscode\mcp.json` file with the following content:
 }
 ```
 
+🔥 To stay up to date with the latest features, you can use our nightly builds. Simply update your `mcp.json` configuration to use `@azure-devops/mcp@next`. Here is an updated example:
+
+```json
+{
+  "inputs": [
+    {
+      "id": "ado_org",
+      "type": "promptString",
+      "description": "Azure DevOps organization name  (e.g. 'contoso')"
+    }
+  ],
+  "servers": {
+    "ado": {
+      "type": "stdio",
+      "command": "npx",
+      "args": ["-y", "@azure-devops/mcp@next", "${input:ado_org}"]
+    }
+  }
+}
+```
+
 Save the file, then click 'Start'.
 
 ![start mcp server](./docs/media/start-mcp-server.gif)