Change KEP status to implemented

Author: xing-yang

keps/sig-storage/177-volume-snapshot/kep.yaml

@@ -7,7 +7,7 @@ authors:
 owning-sig: sig-storage
 participating-sigs:
   - sig-storage
-status: implementable
+status: implemented
 creation-date: 2019-07-09
 reviewers:
   - "@msau42"
@@ -23,7 +23,7 @@ see-also:
   - "keps/sig-storage/1900-volume-snapshot-validation-webhook"
 
 # The target maturity stage in the current dev cycle for this KEP.
-stage: beta
+stage: stable
 
 # The most recent milestone for which work toward delivery of this KEP has been
 # done. This can be the current (upcoming) milestone, if it is being actively