[arch-devops] Refetch fetch-borg-keys

Hi DevOps Team members, This evening I realized we added the offsite backups to rsync.net with borg but never updated the fetch-borg-keys playbook to also download the offsite backup keys (as they are different from the keys for vostok). I've updated the playbook to fetch the offiste borg backup key as $hostname-offsite.gpg. So please re-run them locally and keep the encrypted borg keys somewhere secure :-) For further instructions for fetching the keys check the README. Greetings, Jelle