refs #225: add support for ZSH completion

[mavimo]

Closes #225

@jcassee I added support for ZSH completion, can you check if it work as expected? Thanks!

[jcassee]

@mavimo Thanks for picking up my feature request!

I'm seeing an error when I run the commend:

$ source <(hetzner-kube completion zsh)
_arguments:comparguments:319: can only be called from completion function
_arguments:comparguments:319: can only be called from completion function

(zsh 5.4.2 (x86_64-ubuntu-linux-gnu) on Ubuntu 18.04)

[mavimo]

@jcassee I'm not a ZSH user so it's a bit hard to me to investigate and debug it, can you take a look to the discussion reported in gopasspw/gopass#585 and indicate me if you can find some solution (so I can update the readme on this PR)? Thx!!

[jcassee]

Ah, it's a completion file, not something that can be sourced. I am not sure how to convert it, but this worked:

mkdir ~/.zcomp
fpath=($HOME/.zcomp $fpath)
hetzner-kube completion zsh > ~/.zcomp/_hetzner-kube
rm -f ~/.zcompdump
compinit

This might be good enough?

Edit: fixed commands.

[mavimo]

@jcassee thx!! 🎉

[jcassee]

@mavimo Thank you for the PR.

I see copied the wrong piece of command line history. Fixed it now.

[xetys]

LGTM

[mavimo]

@xetys hemm.. i need to fix the docs 😄

I'll open a new PR asap