added docs about AdminView.

docs/index.rst

@@ -84,6 +84,7 @@ Reference
    ref/forms
    ref/permissions
    ref/views
+   ref/modeladmin
    ref/built-in-views
    ref/renderers
    ref/meta

docs/ref/modeladmin.rst

@@ -0,0 +1,54 @@
+===========
+ModelAdmin2
+===========
+
+The `ModelAdmin2` class is the representation of a model in the admin interface. These are stored in a file named `admin2.py` in your application. Let’s take a look at a very simple example of the ModelAdmin2:
+
+.. code-block:: python
+
+    from .models import Post
+    import djadmin2
+
+    class PostAdmin(djadmin2.ModelAdmin2):
+        pass
+
+    djadmin2.default.register(Post, PostAdmin)
+
+Adding a new view
+=================
+
+To add a new view to a ModelAdmin2, it's need add an attribute that is an
+instance of the `views.AdminView`.
+
+The `view.AdminView` takes tree parameters: `url`, `view` and `name`.
+The `url` is expected a string for the url pattern for your view.
+The `view` is expected a view and `name` is an optional parameter and
+is expected a string that is the name of your view.
+
+.. code-block:: python
+
+    from .models import Post
+    from djadmin2 import views
+    import djadmin2
+
+    class PostAdmin(djadmin2.ModelAdmin2):
+        preview_post = views.AdminView(r'^preview/$', views.PreviewPostView)
+
+    djadmin2.default.register(Post, PostAdmin)
+
+Replacing an existing view
+==========================
+
+To replacing an existing admin view, it's need add an attribute with the same name that
+the view that you want replace:
+
+.. code-block:: python
+
+    from .models import Post
+    from djadmin2 import views
+    import djadmin2
+
+    class PostAdmin(djadmin2.ModelAdmin2):
+        create_view = views.AdminView(r'^create/$', views.MyCustomCreateView)
+
+    djadmin2.default.register(Post, PostAdmin)