dnscache: allow query by freifunk range

hosts/containers/dnscache/configuration.nix

@@ -74,6 +74,7 @@
       "::1/128"
       "172.20.72.0/21"
       "10.0.0.0/24"
+      "10.200.0.0/15"
       "172.22.99.0/24"
       "127.0.0.0/8"
     ];