[Question] Using a Single Config to Snapshot & Backup Multiple Volumes

Thank you very much for creating this tool. It has made diving in to BTRFS (relatively) painless.

I am wondering if a single config file can be used to initiate the backup of multiple BTRFS volumes (e.g. multple HDD's) and selected subvolumes on those disks, or if it is required to create a config file for each.

For example, would this work to create a snapshots in `/smnt/ssd/btrbk_snapshots` and `/mnt/hdd/btrbk_snapshots`, and then create backups in `/mnt/backupdisk/ssd_backup` and `/mnt/backupdisk/hdd_backup`

```
snapshot_dir btrbk_snapshots

volume /mnt/ssd
target /mnt/backupdisk/ssd_backup
subvolume ssd_sub_1
subvolume ssd_sub_1

volume /mnt/hdd
target /mnt/backupdisk/hdd_backup
subvolume hdd_sub_1
subvolume hdd_sub_1
```

Alternatively, is there a different way that I should be structuring things to accomplish the same using a single config?