Define navigational tracking as "without the user's knowledge"?

[jyasskin]

@johannhof pointed out that federated login intrinsically "identif[ies] that a user on one site is the
same person as a user on another site", which is how #2 defines navigational tracking. If we want to say that navigational tracking is always bad, we need some carve-out for cases where the user intentionally copies their identity using a navigation.

Alternatively, we could say that federated login is tracking, but a kind that's not bad. Then we might need yet another term to be the thing we think is bad.

[jwrosewell]

I made a pull request to start adding this into the document.

IMO Tightly defining "good" and "bad" is an important next step.