Running ad-hoc commands in background

This issue was fixed long ago, and you can remove the notice.

Also, I would clarify the way this feature works with a demo, for example, in the case:

```sh
ansible all -B 60 -P 1 -m shell -a "while true; do echo test; sleep 1; done"
```

I expected Ansible to show new `test` lines every second in the terminal 😆
I thought it was the bug you were talking about 🙂 and soon realized I wanted too much from Ansible.