doc: added more detail on customizing to kivy/resource.py

Refrences #82

Seems to work. It's defintie

kivy/resources.py

@@ -2,9 +2,30 @@
 Resources management
 ====================
 
-Resource management can be a pain if you have multiple paths and projects. Kivy
-offers 2 functions for searching for specific resources across a list of
-paths.
+Resource management can be a pain if you have multiple paths and projects.
+Kivy offers 2 functions for searching for specific resources across a list
+of paths.
+
+Resource lookup
+---------------
+
+When Kivy looks for a resource e.g. an image or a kv file, it searches through
+a predetermined set of folders. You can modify this folder list using the
+:meth:`resource_add_path` and :meth:`resource_remove_path` functions.
+
+Customizing Kivy
+----------------
+
+These functions can also be helpful if you want to replace standard Kivy
+resources with your own. For example, if you wish to customize or re-style
+Kivy, you can force your *style.kv* or *data/defaulttheme-0.png* files to be
+used in preference to the defaults simply by adding the path to your preferred
+alternatives via the :meth:`resource_add_path` method.
+
+As almost all Kivy resources are looked up using the :meth:`resource_find`, so
+you can use this approach to add fonts and keyboard layouts and to replace
+images and icons.
+
 '''
 
 __all__ = ('resource_find', 'resource_add_path', 'resource_remove_path')