Add documentation for Kotlin
Add documentation for Kotlin

ArchUnit works with Kotlin mostly out of the box, but there are some
syntax changes (aka workarounds) necessary. Now they're documented.

Signed-off-by: Fabian Winter <a3827a8d25a5b775994b437b0960021107fddae1@tngtech.com>

TNG/ArchUnit,TNG/ArchUnit