Open points:
- [x] Fix documentation (blocked until Phil is done with the doc work)
- [x] layers.enabled and layers.includeLayerTools
- [x] spring-boot-jarmode-layertools has been renamed to spring-boot-jarmode-tools
- [x] Add note to release notes that layers.enabled = false no longer prevents the inclusion of the spring-boot-jarmode-layertools JAR
- [x] Update "Unpacking the Executable JAR" to use the new extract command instead of fiddling with the JarLauncher or constructing the classpath yourself.