Fix license badge

Author: dacoto

readme.md

@@ -1,7 +1,7 @@
 # Laravel Domain Validation
 
 ![GitHub Workflow Status (branch)](https://img.shields.io/github/workflow/status/dacoto/laravel-domain-validation/CI/master)
-![GitHub](https://img.shields.io/github/license/dacoto/laravel-domain-validation)
+[![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
 ![GitHub release (latest by date)](https://img.shields.io/github/v/release/dacoto/laravel-domain-validation)
 
 A domain validator rule for Laravel 6.x and higher.