Merge pull request kubernetes#4227 from aramase/aramase/f/cluster_trust_bundle_kep_update

KEP-3257: Cluster trust bundle: fix path and update alpha milestone

Author: k8s-ci-robot

keps/sig-auth/3257-trust-anchor-sets/README.md renamed to keps/sig-auth/3257-cluster-trust-bundles/README.md

@@ -27,11 +27,11 @@ stage: alpha
 # 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
 # worked on.
-latest-milestone: "v1.27"
+latest-milestone: "v1.29"
 
 # The milestone at which this feature was, or is targeted to be, at each stage.
 milestone:
-  alpha: "v1.27"
+  alpha: "v1.29"
   beta: ""
   stable: ""