Update authz document (#2954)

* update authorizationPolicy CUSTOM action feature status

* update authorizationPolicy CUSTOM action feature status

Author: hzxuzhonghu

security/v1/authorization_policy.pb.go

@@ -512,8 +512,6 @@ message AuthorizationPolicy {
     // One example use case of the extension is to integrate with a custom external authorization system to delegate
     // the authorization decision to it.
     //
-    // Note: The CUSTOM action is currently an **alpha feature** and is subject to breaking changes in later versions.
-    //
     // The following authorization policy applies to an ingress gateway and delegates the authorization check to a named extension
     // "my-custom-authz" if the request path has prefix "/admin/".
     //

security/v1/authorization_policy.proto

@@ -512,8 +512,6 @@ message AuthorizationPolicy {
     // One example use case of the extension is to integrate with a custom external authorization system to delegate
     // the authorization decision to it.
     //
-    // Note: The CUSTOM action is currently an **alpha feature** and is subject to breaking changes in later versions.
-    //
     // The following authorization policy applies to an ingress gateway and delegates the authorization check to a named extension
     // "my-custom-authz" if the request path has prefix "/admin/".
     //