Kotlin website - https://goo.gl/W6bJJJ
Kotlin and Android documentation - https://goo.gl/NWt6O7
Android announced full support for the Kotlin language at Google I/O along with an increased commitment to both the Java programming language and C++. This video interviewed key stakeholders involved with the decision from both Google and Jetbrains to help understand why this decision was made and what it means to the Android developer community.
Introduction to Kotlin (Google I/O '17)
Life is Great and Everything Will Be Ok, Kotlin is Here (Google I/O '17)