docs: improve description

Author: kenjis

user_guide_src/source/changelogs/v4.4.0.rst

@@ -34,8 +34,8 @@ The next segment (``+1``) of the current last segment can be set as before.
 Factories
 ---------
 
-Passing Fully Qualified Classname
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Passing Classname with Namespace
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 Now ``preferApp`` works only when you request
 :ref:`a classname without a namespace <factories-passing-classname-without-namespace>`.
@@ -53,6 +53,15 @@ For example, when you call ``model(\Myth\Auth\Models\UserModel::class)`` or
       - returns ``Myth\Auth\Models\UserModel`` even if ``preferApp`` is true (default)
       - returns ``App\Models\UserModel`` if you define ``Factories::define('models', 'Myth\Auth\Models\UserModel', 'App\Models\UserModel')`` before calling the ``model()``
 
+If you had passed a non-existent classname by mistake, the previous version
+would have returned a class instance in the ``App`` or ``Config`` namespace
+because of the ``preferApp`` feature.
+
+For example, in a controller (``namespace App\Controllers``), if you call
+``config(Config\App::class)`` by mistake (note that you forgot the leading ``\``
+in ``Config\App::class``), that means you pass ``App\Controllers\Config\App``.
+But the class does not exist, so now Factories return ``null``.
+
 Property Name
 ^^^^^^^^^^^^^
 

user_guide_src/source/installation/upgrade_440.rst

@@ -85,10 +85,10 @@ This bug was fixed and now URIs for underscores (**foo_bar**) is not accessible.
 If you have links to URIs for underscores (**foo_bar**), update them with URIs
 for dashes (**foo-bar**).
 
-When Passing Fully Qualified Classnames to Factories
-====================================================
+When Passing Classname with Namespace to Factories
+==================================================
 
-The behavior of passing fully qualified classnames to Factories has been changed.
+The behavior of passing a classname with a namespace to Factories has been changed.
 See :ref:`ChangeLog <v440-factories>` for details.
 
 If you have code like ``model('\Myth\Auth\Models\UserModel::class')`` or