Hi there... this patch is a proof of concept, and probably entirely the wrong approach since I was learning Makefiles almost from scratch as I was doing it (and then by the end realized it only works with recent versions of Make). But I'd like to put the basic idea of the change up for review at least before I continue working on it.
The basic idea is that the Mercurial reference page is too damn big and unwieldy. Its size also makes it hard to search for something only for a given command. One could search through the help output in a terminal but there is tremendous value in having a well organized and friendly website. Anyway, this change makes it possible to spit out separate web pages for each command, topic, and extension, along with a classified index page that links to all of them.