Documentation improvements

The cmdlib documentation hasn't been touched in years. In the current state of the documentation, it's unclear where cmdlib fits into the broader context of DUNE DAQ, particularly the v5/drunc world. I would appreciate an expert review of the documentation. The current examples and code snippets should be checked to see if they're outdated. Also, the docs should provide more context on commands and commanded objects for non experts, beyond the fact that they're json files. Where and how are they used? Who would need to write one?

Start by reviewing the current cmdlib documentation, examples, and code snippets, then compare their context with the DUNE DAQ v5/drunc world. Done means the documentation explains commands and commanded objects, their usage and intended authors, and identifies or updates outdated material.