The argument described here is not documented when documentation generated with yard-tomdoc
Hmm... you switched to pure YARD. (Yea, I use it for most of my projects too). But I've (finally) almost got yard-tomdoc all fixed up, so that might start to change. I assume you mean it wasn't documenting the zmq_io_threads parameter? It may be that it is having trouble with the multiple line description. I'll check it out. Let me know if I've misunderstood. Thanks.
This has been fixed with latest release. Thanks for reporting!
Thank you :)