Gumroad has published a guide for self publishing. Who isn’t interested in self publishing in 2015?
If you publish your own writing of any sort online, there’s a good chance that you’ve entertained the idea of putting out a book. This guide from the Gumroad team covers formats, then the tools that you can use to produce your book.
Sadly, the list is a little lacking. Many writing apps today, such as Ulysses, do a nice job of preparing your content for export. And there are plenty of new services targeted at this need as well. A more detailed article may be more useful.