* zplug: update the output path
This is a breaking change because the old behavior pollutes the nix profile root
dir with all files in https://github.com/zplug/zplug and needs to be fixed.
I created a corresponding PR in the home manager repo
https://github.com/nix-community/home-manager/pull/3922. For non HM users, they
will need to update their dependency on `${pkgs.zplug}/init.zsh` to `${pkgs.zplug}/share/zplug/init.zsh`.
* Only add necessary files to $out/share/zplug. Also add the zplug man pages
The LICENSE file is not in the 2.4.2 tag and there's not a release after that. I
would skip adding the license $out/licenses/zplug in this commit.
Reference: https://aur.archlinux.org/cgit/aur.git/tree/PKGBUILD?h=zplug
