Add zsh

[sadan4]

It's a very common login shell and has differences from bash/sh

Provide links to different compilers/interpreters that could be used to implement this language, and discuss pros/cons of each.

only really one compiler/interpreter

https://www.zsh.org/
github mirror
https://github.com/zsh-users/zsh

[ccall48]

feel free to add it and send a pr