The KDoc contains links as to some package and Kotlin file, but I can't see such packages and files actually
Documentation window screenshot
I looked through the Google Maven repository, expecting to find that I just haven't included some package in my build.gradle, but there were no such artifacts as well
You can find the samples by following package name in the AndroidX repository.
In this case
androidx.compose.foundation.layout.samples.SpacerExamplesample can be found here.As to KDoc problem, it's a known bug