Missing delay function for retry documentation.

[fudom]

It would be great if we find something about delay option with a function for the retry operator. Especially since retryWhen is deprecated. The example should explain how to use the delay function and correct return value in conditional context like retryWhen. Currently there is only one example with simple retry(2). And in the deprecated info of retryWhen where is only retry({ delay: () => notify$ }). Background: I need to migrate an Angular HTTP interceptor for conditional state error handling where no retry is needed. In my opinion it is very important to show such examples, especially when good things from RXJS suddenly become deprecated.