The jq website, manpages and some of the tests are generated from this directory. The directory holds a Bonsai website, and the manual is a YAML file in content/3.manual.
To build the documentation (including building the jq manpage), you'll need a working Ruby setup. The easiest way to get one is to install RVM and Ruby 1.9.3 like so:
\curl -L https://get.rvm.io | bash -s stable --ruby=1.9.3
After that finishes installing, you'll need to make sure RVM is on your path by doing source $HOME/.rvm/scripts/rvm, or just opening a new shell. See https://rvm.io for more info on RVM.
Once RVM is installed, you can install all the dependencies for jq's documentation build by running this from the docs directory:
bundle install
When bundle manages to install the dependencies, rerun ./configure in the jq root directory and then the Makefile will be able to generate the jq manpage.