Kustomization: garbage collection

[disconn3ct]

Given the confusion around resources being changed and re-annotated (fluxcd/flux2#626 fluxcd/kustomize-controller#403 fluxcd/kustomize-controller#213 etc) perhaps it would be helpful to have a warning in the GC section of the documentation. With phrasing styling from HelmReleases, something similar to:

To enable garbage collection, set spec.prune to true.

There is one caveat you should be aware of: the changing labels will cause generated objects to report configured (changed) on every new source repository commit, regardless of the impact of the commit.