Add coverage badge

Author: Jordan Hall

README.md

@@ -1,5 +1,6 @@
 # PHP Word Info
 
 [![Build Status](https://travis-ci.org/DivineOmega/php-word-info.svg?branch=master)](https://travis-ci.org/DivineOmega/php-word-info)
+[![Coverage Status](https://coveralls.io/repos/github/DivineOmega/php-word-info/badge.svg?branch=master)](https://coveralls.io/github/DivineOmega/php-word-info?branch=master)
 
 PHP library to look up information about words