Add example docker-compose setup to repo?

[zorbathut]

While https://www.modem7.com/books/docker-backup/page/backup-docker-using-borgmatic is well-written, I am personally the kind of person who works a lot better with a little example than I am with instructions. Would there be interest in adding a small minimally-functional example setup to the repo? I'm happy to send a pull request if so.

If not, and if I made my own repo with an example, would you be willing to link to it?

[grantbevis]

A PR would be best