Add a configuration section

Author: gallib

README.md

@@ -19,6 +19,12 @@ php artisan migrate
 
 finally, paste ``` ShortUrl::routes(); ``` at the end of ``` routes/web.php ```
 
+## Configuration
+
+Laravel Short Url configuration file could be found on ``` config/shorturl.php ```
+
+-- **blacklist** : Allows to blacklist urls. Keywords can be either an url, a keyword or an extension
+
 ### Advanced configuration
 
 Instead of adding ``` ShortUrl::routes(); ``` you can call three separates methods: