CloudFlare has improved its API, and as of [Certbot 1.6.0][1] (2020-07-07),
Certbot no longer requires permissions on all zones in your CloudFlare account.
(See PR certbot/certbot#8015.)
Verified in Let's Encrypt Add-on 4.11.0 running in Home Assistant 0.118.4.
[1]: https://github.com/certbot/certbot/releases/tag/v1.6.0
Give more details about the API Key requirements for DNS challenge with OVH, following [certbot documentation](https://certbot-dns-ovh.readthedocs.io/en/stable/).
Added example configuration and details about api_endpoint.