nixos/onlyoffice: fix nginx syntax error (#444037)

              '';

            "~* ^(\\/cache\\/files.*)(\\/.*)".extraConfig = ''

              alias /var/lib/onlyoffice/documentserver/App_Data$1;

              more_set_headers Content-Disposition "attachment; filename*=UTF-8''$arg_filename";

              more_set_headers "Content-Disposition: attachment; filename*=UTF-8''$arg_filename";

              set $secure_link_secret verysecretstring;

              secure_link $arg_md5,$arg_expires;