The ZooKeeper website is built using Jekyll formatted in Markdown. The production website is updated using gitpubsub via the zookeeper.git/asf-site branch.
The source to generate the website can be found here: https://github.com/apache/zookeeper/tree/website
The live website is whatever is committed to asf-site, here: https://github.com/apache/zookeeper/tree/asf-site . Any changed committed to this branch are immediately replicated to the live production website at http://zookeeper.apache.org/
Information on running the website generation process can be found in the README.md file on the website branch, similar for managing the asf-site.