How to define groups?

[jcornaz]

I see that some commands of the CLI have a --group option. But I cannot figure out how to define a daemon group.

What is a group exactly, and how can I define one?

[gaojunran]

I've forgotten to add them to docs. Later I'll add them! Thank you for your report!

[jcornaz]

Note it is also missing from the config schema