Gradle-play-publisher: Provide Gradle Kotlin DSL examples in documentation

[eriwen]

Is your feature request related to a problem? Please describe.
No

Describe the solution you'd like
As a Gradle Kotlin DSL adopter, I'd like to know how to configure this plugin using the Kotlin DSL.

Describe alternatives you've considered
N/A

Additional context
This plugin was identified as one of the most useful Gradle plugins. With Kotlin DSL 1.0 approaching shortly, it'd be wonderful if the documentation provided Kotlin and Groovy DSL samples. Blog post with suggestions.

Here are a couple additional resources:

• Migrating build logic from Groovy to Kotlin guide
• Exemplar for automated samples testing
• Join #kotlin-dsl channel in Gradle Community Slack for personalized help

Thank you for providing a great Gradle plugin! —The Gradle Team

[SUPERCILEX]

Part 1: #446
Part 2: #447

[eriwen]

Very nice!