docs: fix incorrect sample code

Author: kenjis

user_guide_src/source/general/logging.rst

@@ -97,7 +97,7 @@ into the message string::
     // Generates a message like: User 123 logged into the system from 127.0.0.1
     $info = [
         'id' => $user->id,
-        'ip_address' => $this->request->ip_address()
+        'ip_address' => $this->request->getIPAddress()
     ];
 
     log_message('info', 'User {id} logged into the system from {ip_address}', $info);