The system documentation is currently rewritten in a new system that builds HTML from ReStructuredText/Sphinx sources.
The git-Repository is at http://git.cacert.org/gitweb/?p=cacert-infradocs.git.
The generated documentation is published to https://infradocs.cacert.org.
Instructions on how to work on the new documentation are available at https://infradocs.cacert.org/building.html.
For some more background information see the mailing list thread at https://lists.cacert.org/wws/arc/cacert-sysadm/2016-05/msg00000.html.
The documentation for this system has been moved to https://infradocs.cacert.org/systems/cats.html