Added detailed walkthrough to docset generation

I don't think we should be instructing people to build the documentation by hand; that is one of the reasons we went through the work of integrating it into the build process. This ensures that they are _always_ up to date, and since they are contained within the repository, it's easy to uninstall, and changing branches will reflect the actual current state of your installed CocoaBloc. I am otherwise fine with instructions on how to install the dependencies and how to import the docset into Dash.