Only create snapshots for configured subvolumes

A tool for creating snapshots and remote backups of btrfs subvolumes.
More information: <https://digint.ch/btrbk/doc/readme.html>.
Trick copyright: tl;dr; <https://github.com/tldr-pages/tldr>

sudo btrbk snapshot

click the source code to copy install btrbk on any operating system with command-not-found.com