Maven layers documentation is incomplete

[philwebb]

The following isn't really that helpful:

https://docs.spring.io/spring-boot/docs/current/maven-plugin/reference/html/#goals-build-image-parameters-details-layers

We could also do with a link from "Building OCI Images" to "Layered Jars" since it's hidden in the ToC.

[snicoll]

The following isn't really that helpful:

I am not sure what you mean by that. This is a rendering of what the Maven plugin generates and choosing a nested type for a parameter as we've decided is unfortunately not supported by Maven.

[philwebb]

I wasn't sure how we generated it. I was hoping we could link out to the Javadoc of the class

[snicoll]

DocumentPluginGoals is generating the file so we could generate Javadoc links when we detect a matching type.