Merge pull request kubernetes#5037 from mattcary/impl

1847: Update kep.yaml for StatefulSetAutoDeletePVC which was implemented in 1.31

Author: k8s-ci-robot

keps/sig-apps/1847-autoremove-statefulset-pvcs/kep.yaml

@@ -7,7 +7,7 @@ authors:
 owning-sig: sig-apps
 participating-sigs:
   - sig-storage
-status: implementable
+status: implemented
 creation-date: 2020-06-04
 reviewers:
   - "@kow3ns"