Dokka's versioning plugin puts previous versions into the directory named older, which is the default and not configurable at the moment. There was never enough reason to change it or make it configurable, but it now could be used for stdlib to make paths more logical, like this:
https://kotlinlang.org/api/core/version/1.9/kotlin-stdlib/kotlin/-enum/
Or even without any additional dedicated folder:
https://kotlinlang.org/api/core/1.9/kotlin-stdlib/kotlin/-enum/
Instead of current older folder:
https://kotlinlang.org/api/core/older/1.9/kotlin-stdlib/kotlin/-enum/