Clarify that the note about disabling become relevant only when the API reaches GA

Co-authored-by: Mo Khan <[email protected]>
Signed-off-by: m.nabokikh <[email protected]>

Author: nabokihms

keps/sig-auth/3325-self-subject-attributes-review-api/README.md

@@ -167,7 +167,8 @@ rules:
   - create
 ```
 
-This API is enabled by default and can be disabled by using the following kube-apiserver flag:
+After reaching GA, the SelfSubjectAttributesReview API will be enabled by default. 
+If necessary, it will be possible to disable this API by using the following kube-apiserver flag:
 ```
 --runtime-config=authentication.k8s.io/v1alpha1/selfsubjectattributesreviews=false
 ```