Layers configuration XSD is not available 

`https://www.springframework.org/schema/boot/layers/layers-2.5.xsd` is not published under [https://www.springframework.org/schema/boot/layers](https://www.springframework.org/schema/boot/layers).
It is used in the documentation [5.1. Layered Jar or War](https://docs.spring.io/spring-boot/docs/2.5.2/maven-plugin/reference/htmlsingle/#packaging.layers)