Clarify the Graduation Criteria to GA

Author: cici37

keps/sig-api-machinery/2876-crd-validation-expression-language/README.md

@@ -1134,8 +1134,10 @@ We plan to add e2e test under api-machinery for crd expression validation:
 
 #### GA
 
-- Formatted message. This targets in 1.27 and ideally should be in at least one release before going to GA.
-- Scalability evaluation. Evaluate CRD scalability with validation rules against [previous scale target](https://github.com/kubernetes/enhancements/blob/master/keps/sig-api-machinery/95-custom-resource-definitions/README.md#scale-targets-for-ga).
+- Formatted message. This has been added in 1.27.
+- Scalability evaluation. Evaluate CRD scalability with validation rules against [previous scale target](https://github.com/kubernetes/enhancements/blob/master/keps/sig-api-machinery/95-custom-resource-definitions/README.md#scale-targets-for-ga). The evaluation is available [here](https://docs.google.com/document/d/1gU8FfBhKnkmzJUC32NmXMdh4vzbLxb-gkf52O9Un7Cg/edit?usp=sharing)
+- Add optional fields reason and fieldPath into validation rules. 
+- Enable [CEL optional support](https://github.com/google/cel-spec/wiki/proposal-246) with proposed controlled rollout strategy. Ideally it should be in at least one release before going to GA.
 
 ## Production Readiness Review Questionnaire
 

keps/sig-api-machinery/2876-crd-validation-expression-language/kep.yaml

@@ -22,7 +22,7 @@ see-also:
   - "/keps/sig-api-machinery/95-custom-resource-definitions"
 
 # The target maturity stage in the current dev cycle for this KEP.
-stage: stable
+stage: beta
 
 # 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
@@ -33,7 +33,6 @@ latest-milestone: "v1.28"
 milestone:
   alpha: "v1.23"
   beta:  "v1.25"
-  stable: "v1.28"
 
 # The following PRR answers are required at alpha release
 # List the feature gate name and the components for which it must be enabled