Generate the autocompletion script for the specified shell

opa help completion

opa bench

Generate the autocompletion script for bash

Generate the autocompletion script for fish

Generate the autocompletion script for powershell

Generate the autocompletion script for zsh

Name	Description
`bash`	Generate the autocompletion script for bash
`fish`	Generate the autocompletion script for fish
`powershell`	Generate the autocompletion script for powershell
`zsh`	Generate the autocompletion script for zsh