zigbee2mqtt: add upgrade warning

pkgs/servers/zigbee2mqtt/default.nix

@@ -3,6 +3,8 @@ let
   package = (import ./node.nix { inherit pkgs system; }).package;
 in
 package.override rec {
+  # don't upgrade! Newer versions cause stack overflows and fail trunk-combined
+  # see https://github.com/NixOS/nixpkgs/pull/118400
   version = "1.16.2";
   reconstructLock = true;