Calendar/Cloud fix

Fixed URL to the new/current Nextcloud instance, fixed a typo.

web/calendar.html

@@ -9,7 +9,7 @@ layout: default
 	</div>
 	
 	<p align="center">Den Kalender gibt's auch per CalDAV:
-    		<a href="webcal://cloud.chaospott.de/calendar/ical.ics">
+    		<a href="webcal://cloud.chaospott.ru/calendar/ical.ics">
        Chaospott Calendar
     		</a>
 	</p>