Update README.md

README.md

 # Lavacharts 4.0
 [![Total Downloads](https://img.shields.io/packagist/dt/khill/lavacharts.svg?style=plastic)](https://packagist.org/packages/khill/lavacharts)
 [![License](https://img.shields.io/packagist/l/khill/lavacharts.svg?style=plastic)](http://opensource.org/licenses/MIT)
-[![Minimum PHP Version](https://img.shields.io/badge/php-%3E%3D%205.5-8892BF.svg?style=plastic)](https://php.net/)
+[![Minimum PHP Version](https://img.shields.io/badge/php-%3E%3D%205.6-8892BF.svg?style=plastic)](https://php.net/)
 [![Gitter](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/kevinkhill/lavacharts?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge)
 [![PayPal](https://img.shields.io/badge/paypal-donate-yellow.svg?style=plastic)](https://paypal.me/kevinkhill)