Improve ring-doorbell CLI help texts

[cpina]

(ring_doorbell) carles@pinux:~/.venvs$ ring-doorbell --help
[...]
  listen            Listen to push notification like the ones sent to...
  motion-detection  Display ring devices.
  show              Display ring devices.
  videos            Interact with ring videos.

I think that the help text might be wrong or incorrect. I don't have any ring device so I cannot properly test it at the moment.

I've found it while writing a manual page.

[github-actions[bot]]

There hasn't been any activity on this issue recently. This issue has been automatically marked as stale because of that. It will be closed if no further activity occurs. Please make sure to update to the latest ring_doorbell version and check if that solves the issue. Thank you for your contributions.