The post has many links to OpenBSD's man pages, FAQ and manual. But I thought it was quite unsatisfying, even common tasks are missing. Or at least I couldn't find them.
I had a test case in mind while reading the documentation: running a custom web service with Nginx as a reverse-proxy. In the documentation, I couldn't find anything about creating a service. Are we supposed to write a frontend script (in ksh) that accepts various arguments (ie start/reload/...)? And what about the logs of this wrapper? And if I want an auto-restart when my program crashes, I have to find another tool that will wrap and monitor the process? I've done all this tedious work in Linux long ago, and I'm not willing to do it again.
If the question was "Why OpenBSD instead of Linux", I don't think documentation is a good argument. In fact, the only strong response I've read is "to try something a bit different and more niche".
