auto-get root page calendar data

shared/templates/styleguide2/includes/organisms/main_section/district/calendar.html

@@ -5,7 +5,8 @@
     </h2>
     <div class="flex flex-wrap">
       <div class="__js-root flex items-center justify-center h-full mb-4 w-full">
-        <ui-full-calendar events='{{ page.get_fullcalendar_data }}'></ui-full-calendar>
+        {% firstof page.get_fullcalendar_data page.root_page.get_fullcalendar_data as calendar_data %}
+        <ui-full-calendar events='{{ calendar_data }}'></ui-full-calendar>
       </div>
     </div>
     <div></div>