My implementation of a markup language, plus rendering code for the UI, is now in a minimally usable state. Here is some sample output, showing a non-sensical help article being rendered:
Here is what the markup language looks like.
Next up for the help system is updating the HTML stream for the extended stream output protocol, and implementing the help article database. However, I'm going to put the help system aside for now, and finish the AMD64 port.