WIP: add notes for missing persistence/backup

TODO:
* Look at for more inspiration https://github.com/nix-community/impermanence/pull/108
* Do home-manager
* Common files https://github.com/nix-community/impermanence/issues/10

modules/nixos/services/grocy/default.nix

@@ -37,6 +37,9 @@ in
       useACMEHost = config.networking.domain;
     };
 
+    # FIXME: backup
+    # FIXME: persistence
+
     # NOTE: unfortunately grocy does not log connection failures for fail2ban
   };
 }