Update README.md

Author: Tom

README.md

@@ -2,7 +2,7 @@ Robots.txt checker
 ==================
 
 [![Build Status](https://travis-ci.org/tomverran/robots.svg?branch=master)](https://travis-ci.org/tomverran/robots)
-[![Packagist](https://img.shields.io/packagist/v/tomverran/robots-txt-checker.svg)]
+[![Packagist](https://img.shields.io/packagist/v/tomverran/robots-txt-checker.svg)](https://packagist.org/packages/tomverran/robots-txt-checker)
 
 Given a robots.txt file this library will give you a straight forward yes/no as to whether you're allowed to access
 a given resource with a given user agent.