Add example of configuration arguments using Maven in Kotlin example

还没有人认领这个 Issue。

Can we get added to the [`pom.xml`](https://github.com/mapstruct/mapstruct-examples/blob/master/mapstruct-kotlin/pom.xml) file in the [kotlin example](https://github.com/mapstruct/mapstruct-examples/tree/master/mapstruct-kotlin) some configuration arguments?

Right now I have the following and it's not working...because `kapt` is being used rather than the maven compiler plugin for annotation processing _(and after a lot of googling and searching, I can't find anything on how `kapt` processor args are meant to be formatted when using maven)_:

```xml
...


org.mapstruct
mapstruct-processor
${mapstruct.version}



-Amapstruct.defaultComponentModel=spring
-Amapstruct.unmappedTargetPolicy=IGNORE
-Amapstruct.suppressGeneratorTimestamp=true
-Amapstruct.suppressGeneratorVersionInfoComment=true

...
```

从 mapstruct-kotlin/pom.xml 开始，将其注解处理器配置与所请求的 MapStruct 参数进行比较。验证示例的 Maven 配置接受列出的参数，并且 Kotlin 示例仍能成功构建；完成意味着该配置作为一个可用示例存在。

由索引模型根据 Issue 内容生成。