Small Action View Overview guide grammar and readability tweaks

I went through the Action Controller Overview guide making a few small changes to improve its grammar and readability (I hope!)
Well, to me, the point of the statement is that a typical application will have a *small* number of layouts. i.e., this is a distinction from views, for example, of which it'll have a great many. "If you're trying to picture a prototypical Rails application, assume it has ~2 layouts" doesn't strike me as untrue -- though that certainly doesn't prevent one from creating an *atypical* application.

I think what I'm [rather poorly] saying is: I agree that that phrasing is prescriptive, but to me, that's the role of this guide: if your application has an open-ended number of layouts -- some number that wouldn't fit "a couple" / "a few" / similar -- then *You're* (probably) *Doing It Wrong* [1]. You can do it, but "typical" you ain't. And if you truly know better, you're probably past taking firm cues from this guide.

[1] **wrong** *(adj)* -- not how DHH would do it :grinning: