Add authenticated decorator to handlers in doc

[fcollonval]

I think it would be good to recommend using the authenticated decorator in the documentation examples for the extension handlers.

[Zsailer]

Ah, that's a great point—though, it adds some extra complexity to the example without explanation.

Do you mind adding a sentence somewhere (maybe a parenthetical) in these docs to help acknowledge why the decorator is there? Maybe a sentence like:
"(it's best practice to wrap each handler method with the "authenticated" decorator to ensure that each request is authenticated by the server)".

[fcollonval]

Thanks for the review and the sentence 😜 @Zsailer

[Zsailer]

LGTM! Thanks, @fcollonval