Zsh was undocumented in Ubuntu 14 because a bug in the package prevented the manuals from being installed and due to the way Canonical handles packages it was never fixed for the entirety of Ubuntu 14.

I am one of those few remaining Zsh users that doesn't have an 200MB baggage train on my shell though. I have a modest (2kb) .zshrc/.zshenv and for the most part just use the builtins.