Good point. Since Kotlin 1.3 (with stable coroutines api) was released recently I doubt you will find a proper book at this time.
Also keep in mind that everything that was released in 1.0, 1.1, 1.2 works in 1.3, so even if you get good book about previous version (eg. Kotlin in Action) it will still do most of the job (even 1.0 book should cover 90% of the existing Kotlin stuff). Then you could simply go through release logs for 1.1, 1.2 and 1.3 to see what has changed to keep up, although coroutines are first change (or rather new feature) of this magnitude in Kotlin, rest of the stuff is mainly compiler optimisations, kotlin plugin optimisations and improved syntax (mostly stuff that you would naturally expect to work after reading 1.0 book)