Update README (in case anyone wants to use dev-master)

Author: shalvah

README.md

@@ -17,7 +17,7 @@ Automatically generate your API documentation from your existing Laravel/Lumen/[
 > Note: version 3.x requires PHP 7 and Laravel 5.5 or higher.
 
 ```sh
-$ composer require mpociot/laravel-apidoc-generator
+$ composer require mpociot/laravel-apidoc-generator:dev-master
 ```
 Using Laravel < 5.5? Go to your `config/app.php` and add the service provider: