docs: add demo gif

README.md

@@ -13,12 +13,12 @@
 <!-- [![Build Status](https://img.shields.io/github/actions/workflow/status/Azure-Samples/serverless-ai-langchainjs/build?style=flat-square)](https://github.com/Azure-Samples/serverless-ai-langchainjs/actions) -->
 <!-- [![Watch how to use this sample on YouTube](https://img.shields.io/badge/YouTube-Watch-d95652.svg?style=flat-square&logo=youtube)]() -->
 
-<!-- TODO: gif demo -->
-
 :star: If you like this sample, star it on GitHub — it helps a lot!
 
 [Overview](#overview) • [Get started](#get-started) • [Run the sample](#run-the-sample) • [Resources](#resources) • [FAQ](#faq) • [Troubleshooting](#troubleshooting)
 
+![Animation showing the chat app in action](./docs/images/demo.gif)
+
 </div>
 
 This sample shows how to build a serverless ChatGPT-like experience with Retrieval-Augmented Generation using [LangChain.js](https://js.langchain.com/) and Azure. The application is hosted on [Azure Static Web Apps](https://learn.microsoft.com/azure/static-web-apps/overview) and [Azure Functions](https://learn.microsoft.com/azure/azure-functions/functions-overview?pivots=programming-language-javascript), with [Azure Cosmos DB for MongoDB vCore](https://learn.microsoft.com/azure/cosmos-db/mongodb/vcore/) as the vector database. You can use it as a starting point for building more complex AI applications.