chore: Add instructions for releasing driver and launcher images (#11179)

Signed-off-by: Chen Sun <chensun@users.noreply.github.com>

Author: chensun

RELEASE.md

@@ -186,6 +186,35 @@ Note, when releasing from master, all the below mentions of "release branch" mea
     - ...
     Set the version by using `VERSION=<version-value>`. Contact @chensun if you are not sure what next version should be.
 
+1. Release `driver` and `launcher` images
+
+   First build and push `driver` and `launcher` images:
+
+   ```bash
+   pushd ./backend
+
+   export IMG_TAG_DRIVER=gcr.io/ml-pipeline/kfp-driver
+   make license_driver image_driver
+   docker push $IMG_TAG_DRIVER
+
+   export IMG_TAG_LAUNCHER=gcr.io/ml-pipeline/kfp-launcher
+   make license_launcher image_launcher
+   docker push $IMG_TAG_LAUNCHER
+
+   popd
+   ```
+
+   If there are changes to the licenses files, make a Pull Request and merge the changes. (e.g. https://github.com/kubeflow/pipelines/pull/11177/)
+
+   Once the images are pushed, update the hard-coded hash in the code: [`DefaultLauncherImage`](https://github.com/kubeflow/pipelines/blob/4c955f4780839702dc4924f8f4e7c90aa251b826/backend/src/v2/compiler/argocompiler/container.go#L33) and [`DefaultDriverImage`](https://github.com/kubeflow/pipelines/blob/4c955f4780839702dc4924f8f4e7c90aa251b826/backend/src/v2/compiler/argocompiler/container.go#L35). Make a Pull Request and merge the change (e.g.: https://github.com/kubeflow/pipelines/pull/11178)
+
+   Pull the changes:
+
+   ```bash
+   git checkout $BRANCH
+   git pull upstream $BRANCH
+   ```
+
 1. Update all version refs in release branch by
 
     ```bash