Chat: describe AI Integration demo (#28480)

apps/demos/Demos/Chat/AIAndChatbotIntegration/description.md

@@ -1 +1,18 @@
-Chat is an interactive interface that allows users to send and receive messages in real time.
+This demo uses an AI service and the DevExtreme Chat component to create a chatbot UI.
+
+## Handling dataSource (reloadOnChange: false)
+
+The Chat component's [dataSource](/Documentation/ApiReference/UI_Components/dxChat/Configuration/#dataSource) is a [CustomStore](/Documentation/ApiReference/Data_Layer/CustomStore/) that implements its own load and insert functions. The Chat deactivates [reloadOnChange](/Documentation/ApiReference/UI_Components/dxChat/Configuration/#reloadOnChange) to push updates directly into the store and update the conversation manually. See the [onMessageEntered](/Documentation/ApiReference/UI_Components/dxChat/Configuration/#onMessageEntered) event handler and the `processMessageSending` function to review the code that manages data transfer between the Chat and its data store.
+<!--split-->
+
+## Custom Message Template
+
+The Chat specifies a [messageTemplate](/Documentation/ApiReference/UI_Components/dxChat/Configuration/#messageTemplate) that displays "Copy" and "Regenerate" buttons in bot messages.
+
+## Response Format Conversion: Markdown to HTML
+
+The AI model outputs responses in Markdown, while the Chat requires HTML output. This examples uses the [unified](https://github.com/unifiedjs) plugin library to convert response content. Review `convertToHtml` function code for implementation details.
+
+## Default Caption Customization
+
+The Chat component in this demo displays modified captions when the conversation is empty. The demo uses [localization](/Documentation/Guide/Common/Localization/) techniques to alter built-in text.