Upgrade auf 12

Doc/Sdi/Icinga/icinga.xml

@@ -18,8 +18,8 @@
   <itemizedlist>
     <listitem>
       <para><link
-      xlink:href="https://www.howtoforge.com/how-to-install-icinga-2-monitoring-software-on-debian-11">How
-      to Install Icinga 2 Monitoring Software on Debian 11</link></para>
+      xlink:href="https://www.howtoforge.com/how-to-install-icinga-2-monitoring-software-on-debian-12">
+      How to Install Icinga 2 Monitoring Software on Debian 12</link></para>
 
       <caution>
         <para>Fix <code>admin</code> email in