Update readme

Author: Nicolas Oelgart

README.md

@@ -8,7 +8,7 @@
 
 [![Latest Stable Version](https://img.shields.io/packagist/v/nicoswd/php-rule-parser.svg)](https://packagist.org/packages/nicoswd/php-rule-parser)
 
-*Note:* This is a development branch. Use at own risk until tagged stable.
+If you're using PHP 5, you might want to look at [version 0.4.0](https://github.com/nicoSWD/php-rule-parser/tree/0.4.0).
 
 You're looking at a PHP library to parse and evaluate text based rules with a Javascript-like syntax. This project was born out of the necessity to evaluate hundreds of rules that were originally written and evaluated in JavaScript, and now needed to be evaluated on the server-side, using PHP.