Add live documentation section to README

Added a section about live documentation and screenshot generation.

Author: kojix2

README.md

@@ -27,6 +27,8 @@ You get windows, buttons, text boxes, menus, dialogs, drawing areas, and other s
   </tbody>
 </table>
 
+📸 **Live Documentation**: All screenshots in the README are automatically generated by [GitHub Actions](https://github.com/kojix2/uing/blob/main/.github/workflows/screenshot.yml) on every push, ensuring cross-platform compatibility (Linux, Windows, macOS).
+
 ## Quick Start
 
 Clone the repository: