Documentation missing on payload option #15
Description
I have to send the current token as payload in request body to refresh it.
It took me some time reading the source code to figure out, that a dynamic payload is possible by wrapping a Promise in a function.
This feature should be documented.
Furthermore it appears a bit strange, that neither a simple callback function is used nor an observable directly (as rxjs is used in source) and this promise is converted into an observable later on.