Add note to README.md

Author: Johan Vergeer

README.md

@@ -17,6 +17,7 @@ Currently, the following examples exist:
 * _mapstruct-spi-accessor-naming_: Example on how to use the Service Provider Interface (SPI) for a custom accessor naming strategy.
 * _mapstruct-protobuf3_: Example on how to use protobuf3 with MapStruct
 * _mapstruct-kotlin_: Example on how to use MapStruct with Kotlin using KAPT (Kotlin Annotation Processing Tool)
+* _mapstruct-kotlin-gradle_: Example on how to use MapStruct with Kotlin and Gradle Kotlin DSL using KAPT
 * _mapstruct-jpa-parent-child_: Example on how to use @Context in relation to parent / child relations in JPA)
 * _mapstruct-lookup-entity-with-composed-key_: Shows how an object with composite key can be read from the database in a mapping method.