Updated readme on middleware setup section

included fully qualified name for request middleware in
app/Http/Kernel.php to get it working in laravel 5.5

Author: Tumaini Mosha

README.md

@@ -23,7 +23,7 @@ In `app/Http/Kernel.php`
 ```php
     protected $routeMiddleware = [
             /// Other Middleware
-            'xml' => XmlRequestMiddleware::class,
+            'xml' => \XmlMiddleware\XmlRequestMiddleware::class,
         ];
 ```