add another remote backup guide to readme

Signed-off-by: Simon L <szaimen@e.mail.de>

readme.md

@@ -387,6 +387,7 @@ Not directly but you have multiple options to achieve this:
 - Mount a network FS like SSHFS, SMB or NFS in the directory that you enter in AIO as backup directory
 - Use rsync or rclone for syncing the borg backup archive that AIO creates locally to a remote target (make sure to lock the backup archive correctly before starting the sync; search for "aio-lockfile"; you can find a local example script here: https://github.com/nextcloud/all-in-one#sync-the-backup-regularly-to-another-drive)
 - You can find a well written guide that uses rclone and e.g. BorgBase for remote backups here: https://github.com/nextcloud/all-in-one/discussions/2247
+- Here is another one that utilizes borgmatic and BorgBase for remote backups: https://github.com/nextcloud/all-in-one/discussions/4391
 - create your own backup solution using a script and borg, borgmatic or any other to backup tool for backing up to a remote target (make sure to stop and start the AIO containers correctly following https://github.com/nextcloud/all-in-one#how-to-enable-automatic-updates-without-creating-a-backup-beforehand)
 
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