Fix CAA record example

[Toastyice]

No description provided.

[boomam]

Hi @Toastyice!
Is there a technical reasoning for changing the CAA example to LetsEncrypt?
I had them listed as example records as not everyone uses LetsEncrypt, but if there's a technical reason for it, I don't mind adjusting accordingly, or at least adjusting the code/guide with some commentable lines to show LetsEncrypt as a common example.

[Toastyice]

Hey @boomam, There's no particular reason I chose letsencrypt, that's just what I use. 
I'd just add the data fields to the example. 
Thank you very much for the examples, by the way. That helped me a great deal.