docs: add filename to the Paths

Author: kenjis

user_guide_src/source/installation/upgrade_configuration.rst

@@ -40,13 +40,13 @@ Code Example
 CodeIgniter Version 3.x
 ------------------------
 
-Path: **application/config**:
+Path: **application/config/site.php**:
 
 .. literalinclude:: upgrade_configuration/ci3sample/001.php
 
 CodeIgniter Version 4.x
 -----------------------
 
-Path: **app/Config**:
+Path: **app/Config/Site.php**:
 
 .. literalinclude:: upgrade_configuration/001.php

user_guide_src/source/installation/upgrade_configuration/001.php

@@ -4,7 +4,7 @@
 
 use CodeIgniter\Config\BaseConfig;
 
-class CustomClass extends BaseConfig
+class Site extends BaseConfig
 {
     public $siteName  = 'My Great Site';
     public $siteEmail = 'webmaster@example.com';