Update zsh completion

[desertstsung]

Update zsh completion file aligned to fish

[hpjansson]

Thanks! I'll merge this, but it's still missing a few options like --files, --files0, --label, --grid, --link, as far as I can tell.

[desertstsung]

Thank you :)
Indeed, there are still some options missing both inside zsh and fish according to the source codes, but as you can see, this is my first PR of this repo, I can't tell if my changes follow its code-of-conduct, so the only refeerence was the fish completion file.
Maybe I can draft a fully documented zsh completion file if I grasp my time, and we can disccuss on it. BTW, I'm wondering if we also have a plan on bash completion? I think bash is more common than zsh/fish.

[hpjansson]

No problem. Your changes are fine.

Yes, if you have the time, I'd love to look at full zsh coverage. There's no plan for bash completions, but you're right: we do need one.