In order to build jPOS documentation, AsciiDoctor needs to be installed.
Then use gradle createPdf to create a PDF (which is usually available in proguide-draft.pdf or gradle viewPdf to create and view it in your defaul viewer.
You can also try gradle createHtml (and gradle viewHtml) but the output doesn't look as nice as in PDF format.
You are encouraged to send pull requests with additions, editions and bugfixes to this guide.