Well, the first 10 or so lines define a macro; I suspect the author was not counting those. This is not entirely unfair, since we're also not counting the code Gulp used to give you that nice builder-style API.
I was thrown off by this at first as well -- the text really doesn't match the visual impression. It might be smart to add a qualifier to the docs: "look how simple the macro is, and then look how concise the gulp definitions are after that."
If you're going to boast about "terseness" as a selling point, you should at least ensure your examples actually demonstrate that to be at all true.