docs: update sample code and add about $autoRoutesImproved just in case

Author: kenjis

user_guide_src/source/incoming/routing.rst

@@ -824,9 +824,13 @@ Enable Auto Routing (Legacy)
 
 Since v4.2.0, the auto-routing is disabled by default.
 
-To use it, you need to change the setting ``$autoRoute`` option to true in **app/Config/Routing.php**::
+To use it, you need to change the setting ``$autoRoute`` option to ``true`` in **app/Config/Routing.php**::
+
+    public bool $autoRoute = true;
+
+And set the property ``$autoRoutesImproved`` to ``false`` in **app/Config/Feature.php**::
 
-    $routes->setAutoRoute(true);
+    public bool $autoRoutesImproved = false;
 
 URI Segments (Legacy)
 =====================