Update installation command in README

It's enough to just require the package because it's not distributed via packagist.

Author: slaFFik

README.md

@@ -12,7 +12,6 @@ WPForms coding standards are based on the [WordPress Coding Standards](https://g
 ## Installation
 
 ```
-composer config repositories.repo-name vcs https://github.com/awesomemotive/wpforms-phpcs.git
 composer require awesomemotive/wpforms-phpcs --dev
 ```