kea: add reservation for mkay

hosts/router/206-net-verwaltung.nix

@@ -47,6 +47,12 @@
               data = "10.42.206.1";
             }
           ];
+          reservations = [
+            { # mkay.bula22.de
+              hw-address = "ac:87:a3:0c:70:04";
+              ip-address = "10.42.206.2";
+            }
+          ];
         }
       ];
     };