Don't use keg-only and pouring jargon.

This is unnecessarily confusing to end-users and the "fun" naming doesn't really communicate anything. @mistydemeo and I talked about this.

CC @adamv @mistydemeo @jacknagel @tdsmith @asparagui for thoughts and review.
Thinking about it more: `private` is my favourite description but it still is a "key" that requires "lookup"; what is private, from what, etc.? `unlinked-by-default` or `default-unlinked` describe what's actually going on.