Add non-root user instructions to the Docker Install Engine

[sastorsl]

It would be good to add the instructions for how to allow a non-root user to manage docker to the https://docs.rockylinux.org/gemstones/containers/docker/ page.

Referencing the upstream dockumentation from https://docs.docker.com/engine/install/linux-postinstall/ and their Manage Docker as a non-root user instructions.