Add early-stage disclaimer to README

Author: nickprotop

README.md

@@ -15,6 +15,8 @@
 
 **SharpConsoleUI** is a modern .NET 9 TUI framework that combines Spectre.Console's rich markup with true multi-window capabilities. **Cross-platform from the ground up.** Each window can run on its own dedicated thread, updating independently without blocking others. **Build beautiful UIs with familiar [markup] syntax everywhere.** No complex styling APIs, just `[bold red]text[/]` and it works. The double-buffered console driver built on .NET's native Console API eliminates flicker and ensures smooth rendering. **Any Spectre.Console widget (Tables, BarCharts, Trees, Panels) works as a window control.** Wrap any `IRenderable` and it just works. Direct CharacterBuffer access with PreBufferPaint/PostBufferPaint hooks lets you build custom rendering, visual effects, or even games (the Snake example renders its canvas this way). Fluent builders for windows, controls, and layouts.
 
+> **Note:** This project is still in early days — work in progress and not production-stable yet. Feedback and contributions welcome.
+
 **Visit the project website: [nickprotop.github.io/ConsoleEx](https://nickprotop.github.io/ConsoleEx/)**
 
 **Browse examples with screenshots: [EXAMPLES.md](docs/EXAMPLES.md)**