Placeholding values should be named clear
Placeholding values should be named clear

Since at Cloudflare there're an Account name (Account home -> Configurations -> Account name) and an Email and only email could be used for auth, all values at this README were updated from `my-user` to `my_cloudflare_email` which sounds much clear. 

There're two different keys at Cloudflare's: `Global API Key` and `Origin CA Key`, let's not give any chance to a reader to be confused, we need Global API Key, so this placeholder was renamed to `my_cloudflare_global_api_key` everywhere at this file.
adferrand/docker-letsencrypt-dns