readme vendor publish error fixed

Author: sahin

readme.md

@@ -20,7 +20,7 @@ Pre Laravel 5.5: After updating composer, add the ServiceProvider to the provide
 You need to publish the config for this package. A sample configuration is provided. The defaults will be merged with gateway specific configuration.
 
 ```
-$ php artisan vendor:publish --provider='Barryvdh\Omnipay\ServiceProvider'
+$ php artisan vendor:publish --provider=Barryvdh\Omnipay\ServiceProvider
 ```
 
 To use the Facade (`Omnipay::purchase()` instead of `App::make(`omnipay`)->purchase()`), add that to the facades array.