add reference to node guide

Author: hossam-nasr

articles/azure-functions/durable/durable-functions-node-model-upgrade.md

@@ -13,7 +13,7 @@ zone_pivot_groups: programming-languages-set-functions-nodejs
 # Upgrade your Durable Functions app to version 4 of the Node.js programming model
 
 >[!NOTE]
-> Version 4 of the Node.js programming model is currently in public preview.
+> Version 4 of the Node.js programming model is currently in public preview. Learn more by visiting the Node [Functions developer guide](../functions-reference-node.md?pivots=nodejs-model-v4).
 
 This article provides a guide to upgrade your existing Durable Functions app to newly released version 4 of the Node.js programming model for Azure Functions from the existing version 3. If you're instead interested in creating a brand new v4 app, follow the Visual Studio Code quickstarts for [JavaScript](./quickstart-js-vscode.md?pivots=nodejs-model-v4) and [TypeScript](./quickstart-ts-vscode.md?pivots=nodejs-model-v4). This article uses "TIP" sections to highlight the most important concrete actions you should take to upgrade your app. Before following this guide, make sure you follow the general [version 4 upgrade guide](../functions-node-upgrade-v4.md). You can also learn more about the new v4 programming model through the [Node.js developer reference](../functions-reference-node.md?pivots=nodejs-model-v4).