Add the media_page plugin to the docs.

docs/plugins.rst

@@ -94,6 +94,11 @@ Copyright plugin
 
 .. automodule:: sigal.plugins.copyright
 
+Media page plugin
+=================
+
+.. automodule:: sigal.plugins.media_page
+
 Upload to S3 plugin
 ===================
 

sigal/plugins/media_page.py

@@ -21,13 +21,19 @@
 # FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 # IN THE SOFTWARE.
 
-import os
+"""Plugin which generates HTML pages for each image.
+
+Currently this plugin can be used only with the colorbox theme, the other
+themes have to be adapted.
+
+For themes, the ``previous_media`` and ``next_media`` variables contain the
+previous/next :class:`~sigal.gallery.Media` objects.
 
-"""Plugin which generates pages for each image.
 """
 
 import codecs
 import logging
+import os
 
 from sigal import signals
 from sigal.writer import Writer