docs: update outdated sample code

Author: kenjis

user_guide_src/source/helpers/filesystem_helper/010.php

@@ -1,3 +1,3 @@
 <?php
 
-$controllers = get_filenames(APPPATH . 'controllers/');
+$controllers = get_filenames(APPPATH . 'Controllers/');

user_guide_src/source/helpers/filesystem_helper/011.php

@@ -1,3 +1,3 @@
 <?php
 
-$models_info = get_dir_file_info(APPPATH . 'models/');
+$models_info = get_dir_file_info(APPPATH . 'Models/');