Update README.md

Author: barryvdh

README.md

@@ -2,6 +2,7 @@
 
 [![Unit Tests](https://github.com/fruitcake/php-cors/actions/workflows/run-tests.yml/badge.svg)](https://github.com/fruitcake/php-cors/actions)
 [![PHPStan Level 9](https://img.shields.io/badge/PHPStan-Level%209-blue)](https://github.com/fruitcake/php-cors/actions)
+[![Code Coverage](https://img.shields.io/badge/CodeCoverage-100%25-brightgreen)](https://github.com/fruitcake/php-cors/actions/workflows/run-coverage.yml)
 [![Packagist License](https://poser.pugx.org/fruitcake/php-cors/license.png)](http://choosealicense.com/licenses/mit/)
 [![Latest Stable Version](https://poser.pugx.org/fruitcake/php-cors/version.png)](https://packagist.org/packages/fruitcake/php-cors)
 [![Total Downloads](https://poser.pugx.org/fruitcake/php-cors/d/total.png)](https://packagist.org/packages/fruitcake/php-cors)