FIX: correct doc link in footer

frontend/src/components/Footer.vue

@@ -2,7 +2,8 @@
     <footer>
         <hr>
         <p class="pull-right d-print-none">
-            <a target="_blank" href="https://www-net-doku.scc.kit.edu/webapi/release/dnscfg-perms/">
+            <a target="_blank"
+               :href="$sysinfo.host_oper_mode.is_prod?'https://www-net-doku.scc.kit.edu/':`https://www-net-${$sysinfo.host_oper_mode.mode}-doku.scc.kit.edu/`">
                 <font-awesome-icon :icon="['far', 'life-ring']"/>
                 Hilfe/Dokumentation</a> |
             <b-link to="/swagger">