A briefer and possibly more up-to-date documentation is the voc-get manpage. It also contains a list of bugs (which exist).
See the HTML documentation for
For building and installing information as well as traditional files
TODO, see the plain text
documentation in the uppercase files.
For the latest information about voc-get internals, see the source code. This is not a joke, the source code contains lots of comments that hopefully describe well the behavior of a function without forcing you to understand the exact behaviour.
Everything is available on the voc-get web site,