Filled out "Graduation Criteria"

Author: everpeace

keps/sig-node/3619-supplemental-groups-policy/README.md

@@ -108,6 +108,9 @@ tags, and then generate with `hack/update-toc.sh`.
       - [Integration tests](#integration-tests)
       - [e2e tests](#e2e-tests)
   - [Graduation Criteria](#graduation-criteria)
+    - [Alpha](#alpha)
+    - [Beta](#beta)
+    - [GA](#ga)
   - [Upgrade / Downgrade Strategy](#upgrade--downgrade-strategy)
   - [Version Skew Strategy](#version-skew-strategy)
 - [Production Readiness Review Questionnaire](#production-readiness-review-questionnaire)
@@ -671,42 +674,30 @@ functionality is accessed.
 [deprecation-policy]: https://kubernetes.io/docs/reference/using-api/deprecation-policy/
 
 Below are some examples to consider, in addition to the aforementioned [maturity levels][maturity-levels].
+-->
+
+Because this KEP's core implementation(i.e. `SupplementalGroupsPolicy` handling) lies inside of CRI implementations(e.g. containerd, cri-o), the graduation criteria contains the support statuses of the updated CRI by container runtimes.
 
 #### Alpha
 
-- Feature implemented behind a feature flag
-- Initial e2e tests completed and enabled
+- At least one of the most popular Container Runtimes(e.g. containerd) implements the updated CRI and released
+- Feature implemented behind a feature flag based on the Container Runtime
+- Unit tests and initial e2e tests completed and enabled
 
 #### Beta
 
-- Gather feedback from developers and surveys
-- Complete features A, B, C
-- Additional tests are in Testgrid and linked in KEP
+- Several popular Container Runtimes(e.g. containerd and cri-o) support the updated CRI and released
+- Fixed reported bugs from the community
+- Additional integration tests and e2e tests are in Testgrid and linked in KEP
 
 #### GA
 
-- N examples of real-world usage
-- N installs
-- More rigorous forms of testing—e.g., downgrade tests and scalability tests
-- Allowing time for feedback
-
-**Note:** Generally we also wait at least two releases between beta and
-GA/stable, because there's no opportunity for user feedback, or even bug reports,
-in back-to-back releases.
-
-**For non-optional features moving to GA, the graduation criteria must include
-[conformance tests].**
+- At least one of Container Runtimes which is not based on the classic container, gVisor for example, supports the updated CRI and released
+- Assuming no negative user feedback based on production experience, promote after 2 releases in beta.
+- [conformance tests] are added for `SupplementalGroupsPolicy` and `ContainerStatus.User` APIs
 
 [conformance tests]: https://git.k8s.io/community/contributors/devel/sig-architecture/conformance-tests.md
 
-#### Deprecation
-
-- Announce deprecation and support policy of the existing flag
-- Two versions passed since introducing the functionality that deprecates the flag (to address version skew)
-- Address feedback on usage/changed behavior, provided on GitHub issues
-- Deprecate the flag
--->
-
 ### Upgrade / Downgrade Strategy
 
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