timeInterval/timeStamp now operate on the computation, not the immediate, scheduler

[DavidMGross]

See: ReactiveX/RxJava#4178

The documentation is now incorrect at these three pages:

• http://reactivex.io/documentation/operators/timeinterval.html
• http://reactivex.io/documentation/scheduler.html
• http://reactivex.io/documentation/operators/timestamp.html

Also, it's imprecise to say the operators "operate" on that scheduler so much as they use that scheduler to get the time.