Fixed malformed directive in CBV date-based-mixins docs.

docs/ref/class-based-views/mixins-date-based.txt

@@ -5,6 +5,7 @@ Date-based mixins
 .. currentmodule:: django.views.generic.dates
 
 .. note::
+
     All the date formatting attributes in these mixins use
     :func:`~time.strftime` format characters. Do not try to use the format
     characters from the :ttag:`now` template tag as they are not compatible.