Update metadata files for enhancements review

Author: g-gaston

keps/prod-readiness/sig-auth/4872.yaml

@@ -0,0 +1,3 @@
+kep-number: 4872
+alpha:
+  approver: "@liggitt"

keps/sig-auth/4872-harden-kubelet-cert-validation/kep.yaml

@@ -20,13 +20,13 @@ 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: ""
+latest-milestone: "1.34"
 
 # The milestone at which this feature was, or is targeted to be, at each stage.
 milestone:
-  alpha: ""
-  beta: ""
-  stable: ""
+  alpha: "1.34"
+  beta: "1.35"
+  stable: "1.37"
 
 # The following PRR answers are required at alpha release
 # List the feature gate name and the components for which it must be enabled