User-oriented documentation

[jcfreeman2]

If you can see this Issue, it means that the existing documentation for this package has already been added to the official documentation, https://dune-daq-sw.readthedocs.io/en/latest, via its placement in your repo's docs/ directory. The next step is to make sure that the documentation in docs/ tells your package's users (as opposed to developers) everything they need to know about the package. The goal is to get this done for the dunedaq-v2.4.1 release in a couple weeks.

For details/hints please see https://dune-daq-sw.readthedocs.io/en/latest/editing_package_documentation/.