It is still early in development, and the main contributor, Gazebo, is more into making changes than organizing a change log.
The bulk of the mod so far is the happiness system overhaul, which has its own thread if you are interested in how it works. Policy, leader, and building changes have just begun.
We could probably convince someone to make a wikia once we are at a stage where such a thing would be needed. A lot of people like making wikias for some reason.