This fork is one excuse for me to play with XCode on macOS, to chase its code scanning warnings, and basic debugging with an "External Build System" XCode project managing an Autoconf or CMake code base.
original readme as follows:
DISCOUNT is a implementation of John Gruber & Aaron Swartz's Markdown markup language. It implements, as far as I can tell, all of the language as described in http://daringfireball.net/projects/markdown/syntax and passes the Markdown test suite at http://daringfireball.net/projects/downloads/MarkdownTest_1.0.zip
DISCOUNT is free software written by David Parsons orc@pell.portland.or.us; it is released under a BSD-style license that allows you to do as you wish with it as long as you don't attempt to claim it as your own work.
Most of the programs included in the DISCOUNT distribution have manual pages describing how they work.
The file INSTALL describes how to build and install discount