More complex example with multiple subvolumes in multiple directories in howto.

For example LXD backups when there is many existing snapshots in many different directories.

Would "archive" mode work somehow? or when selecting which subvolumes to back up I should use "*" symbol?

**I know that this may not be real issue**, but there is no forum and this would help people who want just to make simple backup of something like LXD.

I shortened list of my LXD subvolumes.

`ID 285 gen 858878 top level 284 path storage-pools/default
ID 286 gen 858878 top level 285 path storage-pools/default/containers
ID 287 gen 858880 top level 285 path storage-pools/default/snapshots
ID 288 gen 856228 top level 285 path storage-pools/default/images
ID 289 gen 430742 top level 285 path storage-pools/default/custom
ID 303 gen 861958 top level 286 path storage-pools/default/containers/wiki
ID 321 gen 861965 top level 286 path storage-pools/default/containers/gitlab
ID 324 gen 861965 top level 286 path storage-pools/default/containers/proxy
ID 334 gen 286130 top level 287 path storage-pools/default/snapshots/XXX/first_btrfs
ID 922 gen 624544 top level 288 path storage-pools/default/images/XXX

`

Start by reviewing the existing howto examples covering subvolume selection and archive mode. Reproduce the documented behavior against the shortened LXD subvolume layout, then clarify whether wildcard selection or archive mode supports it. Done means the howto contains a concrete multi-directory, multi-subvolume example with the required configuration guidance.

Written by the indexing model from the issue text.