KEP-277: Mark as implemented

Author: verb

keps/sig-node/277-ephemeral-containers/kep.yaml

@@ -6,7 +6,7 @@ owning-sig: sig-node
 participating-sigs:
   - sig-auth
   - sig-node
-status: implementable
+status: implemented
 creation-date: 2019-02-12
 reviewers:
   - "@dchen1107"