doc: update release notes for checking image promotion (#149)

Author: ajaysundark

RELEASE.md

@@ -23,21 +23,63 @@ The automation will:
 2. Create and push a git tag `vX.Y.Z` at the merged commit.
 3. If it is a minor or major release (e.g. `v0.2.0`), it will automatically branch off `release-vX.Y.Z` and push it to the repository.
 
-## 3. Create the GitHub Release
+## 3. Promote the Images
 
-- Pushing the tag will trigger the `cloudbuild.yaml` CI to build and publish the container image for the release (e.g., `us-central1-docker.pkg.dev/.../node-readiness-controller:vX.Y.Z`).
-- Go to the [Releases page](https://github.com/kubernetes-sigs/node-readiness-controller/releases) on GitHub.
-- Find the new tag and click "Edit tag" (or "Draft a new release" and select the tag).
-- Paste the final changelog into the release description.
-- Generate the release manifests locally for this version:
+After the release tag is pushed, the images must be built, pushed to staging, and then promoted to the official registry.
+
+### A. Verify Staging Images
+- Monitor the image push job status on [Testgrid (sig-node-image-pushes)](https://testgrid.k8s.io/sig-node-image-pushes#post-node-readiness-controller-push-images).
+- The Prow job configuration is in [test-infra](https://github.com/kubernetes/test-infra/blob/master/config/jobs/image-pushing/k8s-staging-node-readiness-controller.yaml) if troubleshooting is needed.
+- Verify the images exist in the staging repository:
+  ```sh
+  skopeo list-tags docker://us-central1-docker.pkg.dev/k8s-staging-images/node-readiness-controller/node-readiness-controller | grep vX.Y.Z
+  ```
+
+### B. Create PR for Promotion
+- Identify the image digests:
+  ```sh
+  skopeo inspect docker://us-central1-docker.pkg.dev/k8s-staging-images/node-readiness-controller/node-readiness-controller:vX.Y.Z --format '{{.Digest}}'
+  skopeo inspect docker://us-central1-docker.pkg.dev/k8s-staging-images/node-readiness-controller/node-readiness-reporter:vX.Y.Z --format '{{.Digest}}'
+  ```
+- Fork [kubernetes/k8s.io](https://github.com/kubernetes/k8s.io).
+- Update
+  `registry.k8s.io/images/k8s-staging-node-readiness-controller/images.yaml`
+  with the new digests and tags ([sample PR](https://github.com/kubernetes/k8s.io/pull/9176)).
+- Submit the PR to `kubernetes/k8s.io`. Once it is approved and merged
+  automation will schedule the promotion.
+
+## 4. Final Verification and GitHub Release
 
+Before publishing the release, verify the images are available at k8s-registry:
+
+### A. Verify Official Registry
+- Ensure the images are available at `registry.k8s.io`:
+  ```sh
+  skopeo list-tags docker://registry.k8s.io/node-readiness-controller/node-readiness-controller | grep vX.Y.Z
+  ```
+
+### B. Test Release Artifacts
+- Checkout the release tag locally
+  ```sh
+  git show vX.Y.Z -q  # to verify the right tag and commit
+  git checkout vX.Y.Z
+  ```
+- Generate the release manifests:
   ```sh
+  rm -rf ./dist
   make build-installer IMG_PREFIX=registry.k8s.io/node-readiness-controller/node-readiness-controller IMG_TAG=vX.Y.Z
+  ls ./dist   # to confirm the generated artifacts
   ```
-- Upload the generated `dist/crds.yaml`, `dist/install.yaml`, and `dist/install-full.yaml` files as release artifacts.
+- Run a local E2E test in Kind (see `docs/TEST_README.md`) using the generated manifests from the `dist/` directory to ensure they pull the correct images and function as expected.
+
+### C. Create the GitHub Release
+- Go to the [Releases page](https://github.com/kubernetes-sigs/node-readiness-controller/releases) on GitHub.
+- Find the new tag and click "Edit tag" (or "Draft a new release" and select the tag).
+- Paste the final changelog into the release description.
+- Upload the generated  manifests (`dist/crds.yaml`, `dist/install.yaml`, and `dist/install-full.yaml`) as release artifacts.
 - Publish the release.
 
-## 4. Post-Release Tasks
+## 5. Post-Release Tasks
 
 - Close the release tracking issue.
 - Announce the release on the `sig-node` mailing list. The subject should be: `[ANNOUNCE] Node Readiness Controller vX.Y.Z is released`.