Second Edition, page 315 (Chapter 11) #439
Description
The "tip" (or "key") aside at the top of page 315 says "You can use validate option with Ansible's copy, linefile, blockinfile, and template modules."
I think linefile was intended to be lineinfile, as I can't find any linefile module in ansible...
I would also suggest there's a missing the in front of the word validate, but maybe that's just a personal style thing...