docs: fix sample code

Author: kenjis

user_guide_src/source/general/modules/006.php

@@ -1,4 +1,4 @@
 <?php
 
 // Routes.php
-$routes->get('blog', 'Acme\Blog\Controllers\Blog::index');
+$routes->get('blog', '\Acme\Blog\Controllers\Blog::index');