documenting the new media_type plugins and available hooks

docs/source/pluginwriter/media_type_hooks.rst

@@ -0,0 +1,27 @@
+==================
+ Media Type hooks
+==================
+
+This documents the hooks that are currently available for ``media_type`` plugins.
+
+What hooks are available?
+=========================
+
+'sniff_handler'
+---------------
+
+This hook is used by ``sniff_media`` in ``mediagoblin.media_types.__init__``.
+Your media type should return its ``sniff_media`` method when this hook is
+called.
+
+.. Note::
+    Your ``sniff_media`` method should return either the ``media_type`` or
+    ``None``.
+
+'get_media_type_and_manager'
+----------------------------
+
+This hook is used by ``get_media_type_and_manager`` in
+``mediagoblin.media_types.__init__``. When this hook is called, your media type
+plugin should check if it can handle the given extension. If so, your media
+type plugin should return the media type and media manager.