Update README.md

Author: ytake

README.md

@@ -1,6 +1,6 @@
 # Nazg Micro Framework Core Repository
 
-[![Packagist](https://img.shields.io/badge/HHVM-%3E=3.24-orange.svg?style=flat-square)](https://packagist.org/packages/nazg/framework)
+[![Packagist](https://img.shields.io/badge/HHVM-%3E=4.35-orange.svg?style=flat-square)](https://packagist.org/packages/nazg/framework)
 [![Packagist](https://img.shields.io/packagist/l/nazg/framework.svg?style=flat-square)](https://packagist.org/packages/nazg/framework)
 [![Build Status](http://img.shields.io/travis/nazg-hack/framework/master.svg?style=flat-square)](https://travis-ci.org/nazg-hack/framework)