docs: add "Loading a Class in Sub-directories"

Author: kenjis

user_guide_src/source/concepts/factories.rst

@@ -41,10 +41,16 @@ On the other hand, Services have code to create instances, so it can create a co
 that needs other services or class instances. When you get a service, Services require a service name,
 not a class name, so the returned instance can be changed without changing the client code.
 
+Loading Classes
+***************
+
+Loading a Class
+===============
+
 .. _factories-example:
 
-Example
-=======
+Model Example
+-------------
 
 Take a look at **Models** as an example. You can access the Factory specific to Models
 by using the magic static method of the Factories class, ``Factories::models()``.
@@ -79,6 +85,15 @@ you get back the instance as before:
 
 .. literalinclude:: factories/003.php
 
+Loading a Class in Sub-directories
+==================================
+
+If you want to load a class in sub directories, you use the ``/`` as a separator.
+The following code loads **app/Libraries/Sub/SubLib.php**:
+
+.. literalinclude:: factories/013.php
+   :lines: 2-
+
 Convenience Functions
 *********************
 

user_guide_src/source/concepts/factories/013.php

@@ -0,0 +1,3 @@
+<?php
+
+$lib = Factories::libraries('Sub/SubLib');