It would be nice if the first chapter would introduce 10,000 foot picture of content management. What is the generic idea: download content from various resources (RHCDN and 3rd party repositories) onto Foreman Server and Proxies, create environments, promote content and register individual systems to those environments.
We should tell them why we are suggesting that - to isolate environments and have a predictable and managable upgrade paths. I know most of this is explained later, but I believe it is worth explaining this at the very beginning.
Finally, the structure of this book is done in a way that Red Hat content goes first, this could be confusing for upstream users who need to use Custom Content instead. The introduction could reflect that and stress out this for upstream users (and the opposite for downstream users).
Great work. This is another high-quality content made available to upstream users! Thanks so much.