docs: remove outdated important note

Since v4.5.0, you can define App and Config in composer.json.

Author: kenjis

user_guide_src/source/general/managing_apps.rst

@@ -8,21 +8,6 @@ directory. It is possible, however, to have multiple sets of
 applications that share a single CodeIgniter installation, or even to
 rename or relocate your application directory.
 
-.. important:: When you installed CodeIgniter v4.1.9 or before, and if there are ``App\\`` and ``Config\\`` namespaces in your ``/composer.json``'s ``autoload.psr-4`` like the following, you need to remove these lines, and run ``composer dump-autoload``.
-
-    .. code-block:: text
-
-        {
-            ...
-            "autoload": {
-                "psr-4": {
-                    "App\\": "app",             <-- Remove this line
-                    "Config\\": "app/Config"    <-- Remove this line
-                }
-            },
-            ...
-        }
-
 .. contents::
     :local:
     :depth: 2