docs: update sample code

Author: kenjis

user_guide_src/source/installation/upgrade_routing/001.php

@@ -1,16 +1,11 @@
 <?php
 
-namespace Config;
+use CodeIgniter\Router\RouteCollection;
 
-// ...
-
-/*
- * --------------------------------------------------------------------
- * Route Definitions
- * --------------------------------------------------------------------
+/**
+ * @var RouteCollection $routes
  */
-
-// ...
+$routes->get('/', 'Home::index');
 
 $routes->add('posts/index', 'Posts::index');
 $routes->add('teams/create', 'Teams::create');
@@ -21,5 +16,3 @@
 $routes->add('drivers/create', 'Drivers::create');
 $routes->add('drivers/update', 'Drivers::update');
 $routes->add('posts/(:segment)', 'Posts::view/$1');
-
-// ...