Some clarifications added

I added a few tips to help noobs get started with registering helper functions and validations.  Prior to my changes, the docs did not fully demonstrate where to add these rules, so the user was left guessing and googling for possible solutions.
Examples, even bad ones, are better than none, and I'm only trying to remedy the dearth of examples in the docs.  These are things that would have saved me and my team many hours of time had they been explained in the first place.  When "there is no right answer", the pushback on attempted cures to the problems comes across as quite surprising.