Wrote short README and made it a plugin for oh-my-zsh.
Added 'git annex help' which was missing. Not sure why it it shown two times …
Added installation instructions for zsh users.
Reverted changes which did not fix https://github.com/Schnouki/git-annex-zsh-completion/issues/1.
Enhance the completion for the help subcommand
Add --help to common options
Fix the behaviour of -( and -)

Looks bad, but seems to work.