One of the authors here. This website is still a work in progress.
It's an ongoing effort to gather all the resources that will help you use Erlang in a business. The booksite is divided in three sections focusing particularly on Erlang/OTP’s higher level concepts in the current open source ecosystem, how to use it in production (while setting up a pipeline for continuous development and delivery), and how to build a team when you’re starting from scratch.
We're working mostly linearly in each section, but they're not all progressing at the same pace. We have nothing yet on "building a team" although our outlines are all planned; the "hard things to get right" chapter was supposed to come in later but we saw enough questions about these topics to rush it out.
We might release things from each section as they are ready and we see fit. In the meanwhile, we're always appreciating feedback and people checking in to see what's new in terms of content.
I see you mention circuit breakers.
I think they deserve more thorough coverage because 1) you really need them in a lot of applications, and 2) they're not in OTP, so picking one (especially if you're not really an Erlang expert) and employing it in the right way are a bit trickier.
A simple example of an application that probably needs a circuit breaker is a web application that can keep running even if the database is not available, even if all it does is return an error message to the browser.
Don't circuit breakers arise naturally from configuring supervisors in a particular way? I.e. supervisor failover after a certain number/period of retries.