Request for comments: Support for shell autocompletion

[ncreuschling]

I would like to get your feedback whether you would accept a PR for shell autocompletion.

I am in the process of migrating a RubyGems from gli (GitHub) to dry-cli. gli generates output for bash and zsh autocompletion e.g. rubygem-command help -c (see documentation).

I am pretty sure hanami-cli would profit from such a feature as well.

Should I take a shot at this or is this something you are not interested?