edit README.md

Author: ddrv

README.md

@@ -5,7 +5,6 @@
 
 [![Latest Stable Version](https://poser.pugx.org/ddrv/iptool/v/stable?format=flat-square)](https://packagist.org/packages/ddrv/iptool)
 [![Total Downloads](https://poser.pugx.org/ddrv/iptool/downloads?format=flat-square)](https://packagist.org/packages/ddrv/iptool)
-[![Latest Unstable Version](https://poser.pugx.org/ddrv/iptool/v/unstable?format=flat-square)](https://packagist.org/packages/ddrv/iptool)
 [![License](https://poser.pugx.org/ddrv/iptool/license?format=flat-square)](https://packagist.org/packages/ddrv/iptool)
 
 [Documentation](https://github.com/ddrv/iptool/wiki)