I believe that the best way of learn things is to play with them. Learning by example first, then reading and learning more details and theory. I think it's mainly because I'm to dumb to understand the idea or any concept even if it's well described. If I was a Neanderthalian and somebody tried to explain to me what fire is, I would never understand it. I would have to light it on my own few times, get my first burns and first grilled zucchini.
What I'm trying to explain here is ... :) that my adventure with static site generators started, because I could use somebody's work. I could play with it and quickly see what I can do and to quickly set up a sample that I could present in my company to drive a change. Now you have all the links in one place, you don't have to spend to much time on research.
This repo is suppose to give you a bunch of links to themes or ready implementations of documentation portals. They will help you to quickly get some good samples to play with a static site generator that you are interested with.
Why not just templates only? Simply because basing on my experience it is sometimes also good to learn on ready implementations. This is how I understood what generators are. I played with https://github.com/Wiredcraft/carte [Jekyll] and https://github.com/liferay/alloyui.com [DocPad] first, and prepared a proof of concept by setting up the second one locally with my own content.