Update README.md

Author: CodeWithDennis

README.md

@@ -3,6 +3,8 @@
 [![Latest Version on Packagist](https://img.shields.io/packagist/v/codewithdennis/filament-select-tree.svg?style=flat-square)](https://packagist.org/packages/codewithdennis/filament-select-tree)
 [![Total Downloads](https://img.shields.io/packagist/dt/codewithdennis/filament-select-tree.svg?style=flat-square)](https://packagist.org/packages/codewithdennis/filament-select-tree)
 
+If you're using Filament 4.x, check out the compatible version of this package [here](https://github.com/CodeWithDennis/filament-select-tree/tree/4.x).
+
 This package adds a dynamic select tree field to your Laravel / Filament application, allowing you to create interactive hierarchical selection dropdowns based on relationships. It's handy for
 building selection dropdowns with various customization options.