Is your feature request related to a problem? Please describe.
I would like to be able to make database dumps of other database containers running alongside backrest. From what i saw in the code the docker-cli package is a part of the container meaning i can perform this operation from inside of backrest am i right?

Describe the solution you'd like
My only problem is that i wasn't able to find this in the documentation. I'am open to contribute this part to the documentation, i would only need a little guidance so i know where to add this part. I personally proxy the docker connection so i could add this to the documentation as well.