Update README.md

Author: crynobone

README.md

@@ -6,5 +6,6 @@ Updater API for Laravel Dusk ChromeDriver binaries
 [![Total Downloads](https://poser.pugx.org/orchestra/dusk-updater-api/downloads)](https://packagist.org/packages/orchestra/dusk-updater-api)
 [![Latest Unstable Version](https://poser.pugx.org/orchestra/dusk-updater-api/v/unstable)](//packagist.org/packages/orchestra/dusk-updater-api)
 [![License](https://poser.pugx.org/orchestra/dusk-updater-api/license)](https://packagist.org/packages/orchestra/dusk-updater-api)
+[![Coverage Status](https://coveralls.io/repos/github/orchestral/dusk-updater-api/badge.svg?branch=1.x)](https://coveralls.io/github/orchestral/dusk-updater-api?branch=1.x)
 
 `orchestra/dusk-updater-api` package provide a standardise API to fetch and download ChromeDriver binaries for Laravel Dusk.