Zotonic documentation, as it should be.
Building the docs
You need to run
make stubs to generate some stub documents to pull in all doc-* from the modules/ tree.
Also, the generation needs to know where it can find the zotonic sources, which should be defined by the ZOTONIC_SRC environment variable (absolute path, please).
When the stubs are in place, build the html docs by running:
$ make html
make help is there to guide you to what other targets are available.