clarify redirect

Author: BenTheElder

data/announcements/scheduled.yaml

@@ -156,8 +156,8 @@ announcements:
   startTime: 2023-03-27T00:00:00 # This should run after the redirect begins
   endTime: 2023-05-31T00:00:00
   style: "background: #c70202"
-  title: Legacy k8s.gcr.io container image registry will be redirected to registry.k8s.io
+  title: Legacy k8s.gcr.io container image registry is being redirected to registry.k8s.io
   message: |
-    k8s.gcr.io image registry is being redirected to registry.k8s.io (since Monday March 20th).<br>
+    k8s.gcr.io image registry is gradually being redirected to registry.k8s.io (since Monday March 20th).<br>
     All images available in k8s.gcr.io are available at registry.k8s.io.</br>
     Please read our [announcement](/blog/2023/03/10/image-registry-redirect/) for more details.