What's new
- Adding the possibility to add a `main` command
> If you want to run a function without specifying a command, you can use the `main` decorator
> or the `is_main` parameter to the `command` decorator:
>
> python
> cli.command(help='Run without command', is_main=True)
> def run_main():
> pass
>
> or even simpler:
>
> python
> cli.main()
> def run_main():
> pass
>
>
> This will allow you to run the function without specifying a command:
>
> bash
> python -m piou.example.simple_main -h
>
>
> **Note**: You can only have one `main` function in the CLI.
>