Atomic Kotlin is the book and associated learning resources by Bruce Eckel and Svetlana Isakova.
September 1, 2020: The eBook is finished and published on Leanpub. The Stepik version will be available soon, and the print book should appear within the next couple of months.
Announcement during the October 2018 KotlinConf opening keynote:
Current version of the cover for the (upcoming) print book: