nixos/mx-puppet-discord: move into matrix category

nixos/modules/module-list.nix

@@ -559,6 +559,7 @@
   ./services/matrix/mautrix-facebook.nix
   ./services/matrix/mautrix-telegram.nix
   ./services/matrix/mjolnir.nix
+  ./services/matrix/mx-puppet-discord.nix
   ./services/matrix/pantalaimon.nix
   ./services/matrix/synapse.nix
   ./services/misc/airsonic.nix
@@ -626,7 +627,6 @@
   ./services/misc/mediatomb.nix
   ./services/misc/metabase.nix
   ./services/misc/moonraker.nix
-  ./services/misc/mx-puppet-discord.nix
   ./services/misc/n8n.nix
   ./services/misc/nitter.nix
   ./services/misc/nix-daemon.nix