Update custom filters sample code

Author: sammyskills

user_guide_src/source/outgoing/view_parser/012.php

@@ -7,8 +7,8 @@
 class View extends BaseView
 {
     public $filters = [
-        'abs'        => '\CodeIgniter\View\Filters::abs',
-        'capitalize' => '\CodeIgniter\View\Filters::capitalize',
+        'foo'        => '\Some\Class::methodName',
+        'str_repeat' => 'str_repeat', // native php function
     ];
 
     // ...