Tiny protip added

templates/admin/bans/form.html

@@ -10,7 +10,7 @@
                               {'class': 'span4'},
                               {'class': 'span8'}
                              )) }}
-  {{ form_theme.row(form.expires, attrs={'class': 'span12'}) }}
+  {{ form_theme.row(form.expires, attrs={'class': 'span12', 'placeholder': 'YYYY-MM-DD'}) }}
 </fieldset>
 <fieldset>
   <legend>{% trans %}Ban Message{% endtrans %}</legend>