HTML Editor: add AI-powered Text Editing demo description (DevExpress#30080)

Author: vladaskorohodova

apps/demos/Demos/HtmlEditor/AITextEditing/description.md

@@ -1,5 +1,18 @@
-In our upcoming major release (v25.1) we will incorporate AI-powered text editing into the DevExtreme HTML Editor.  
+HTML Editor offers AI-powered text editing. To enable this feature, follow these steps:
+
+1. Link the HTML Editor to an AI service through the aiIntegration option.
+2. Specify the "ai" toolbar item in the toolbar configuration.
+
 <!--split-->
-Users will be able to apply actions to selected content (such as proofreading, summarizing, expanding text, etc) and you will be able to add a custom command to execute a specific request to your selected AI service.  
+The "ai" toolbar item includes the following predefined commands:
+
+- Summarize
+- Proofread
+- Expand
+- Shorten
+- Change style
+- Change tone
+- Translate
+- Ask AI assistant
 
-Our new AI-powered Extensions will be accessed through a dedicated button in the HTML Editor’s toolbar. 
+You can also specify which predefined commands you want to include in the "ai" item and customize the default options (for example, by setting a custom list of target languages for translation). Additionally, you can add a new custom command to the AI item by specifying your own prompt. In this demo, the custom command is "Extract Keywords". For more details, check the prompt in the code.