doc: added image for adapter.py

kivy/adapters/__init__.py

@@ -11,6 +11,9 @@ presented by views. Views are top-level widgets, such as a
 :class:`~kivy.uix.listview.ListView`, that allow users to scroll through
 and (optionally) interact with your data.
 
+The Concept
+-----------
+
 Kivy adapters are modelled on the
 `Adapter design pattern <http://en.wikipedia.org/wiki/Adapter_pattern>`_.
 Conceptually, they play the role of a 'controller' between you data and views
@@ -18,6 +21,16 @@ in a `Model-View-Controller
 <https://en.wikipedia.org/wiki/Model%E2%80%93view%E2%80%93controller>`_
 type architecture.
 
+The role of an adapter can be depicted as follows:
+
+.. image:: images/adapters.png
+
+
+The Components
+--------------
+
+The components involved in this process are:
+
 - **Adapters**: The base :class:`Adapter` is subclassed by the
   :class:`SimpleListAdapter` and :class:`ListAdapter`. The :class:`DictAdapter`
   is a more advanced and flexible subclass of :class:`ListAdapter`.