fix: allow plugin to work with zinit

[iloveitaly]

• zinit does not play well with symlinked completions
• zinit will pick up this completion, which ends up breaking the git completion and preventing the git-completion.zsh from being used

Also, unlike the documentation states, I found that a standard plugin load did not work me. I needed:

blockf ver"zinit-fixed" as"completion" nocompile mv'git-completion.zsh -> _git' iloveitaly/git-completion

[iloveitaly]

@felipec thoughts on this?