shortcutdomains: more shortcuts

tbh, I'm not entirely sure about these — if we have single-letter
domains only, we'll run into trouble pretty quickly (e.g. with
mattermost/mumble). I've kept it limited to only *.infra4future.de,
where that is less of a problem (for now).

services/shortdomains.nix

@@ -15,5 +15,8 @@ in
   services.nginx.virtualHosts = lib.listToAttrs [
     (short "d" "discuss.infra4future.de")
     (short "m" "mattermost.infra4future.de")
+    (short "c" "cloud.infra4future.de")
+    (short "s" "survey.infra4future.de")
+    (short "g" "gitlab.infra4future.de")
   ];
 }