seber: allow different rrsync directories

systems/seber/services/ebil-club.nix

···
           group = name;
           openssh.authorizedKeys.keys = map (
             key:
-            ''command="${pkgs.rrsync}/bin/rrsync ~/${defaultHost}",restrict,no-agent-forwarding,no-port-forwarding,no-pty,no-user-rc,no-X11-forwarding ${key}''
+            ''command="${pkgs.rrsync}/bin/rrsync ~",restrict,no-agent-forwarding,no-port-forwarding,no-pty,no-user-rc,no-X11-forwarding ${key}''
           ) sshPubkeys;
         };
       };