Add docs for new batch system.

And some other tweak(s).

docs/conf.py

@@ -34,6 +34,7 @@ execfile(os.path.join(os.pardir, 'tailbone', '_version.py'))
 extensions = [
     'sphinx.ext.autodoc',
     'sphinx.ext.todo',
+    'sphinx.ext.viewcode',
 ]
 
 # Add any paths that contain templates here, relative to this directory.