manager image patch

Makefile

@@ -96,8 +96,7 @@ docker-push-release:  docker-tag-release
 docker-build:
 	docker build . -t ${IMG}
 	@echo "updating kustomize image patch file for manager resource"
-	cp ./config/manager/manager_image_patch.example.yaml ./config/manager/manager_image_patch.yaml
-	sed -i'' -e 's@image: .*@image: '"${IMG}"'@' ./config/manager/manager_image_patch.yaml
+	echo "#" > ./config/manager/manager_image_patch.yaml
 
 docker-build-ci:
 	docker build . -t $(IMG) -f Dockerfile_ci

README.md

@@ -62,14 +62,14 @@ Currently the most reliable way of installing Gatekeeper is to build and install
 
 #### Deploying a Release using Prebuilt Image
 
-  If you want to deploy a released version of Gatekeeper in your cluster with a prebuilt image, then you can run the following command, substituting the url to your prebuilt image:
-
-  ```
-  IMG=<YOUR DESIRED PREBUILT IMAGE URL>
-	cp ./config/manager/manager_image_patch.example.yaml ./config/manager/manager_image_patch.yaml
-	sed -i'' -e 's@image: .*@image: '"${IMG}"'@' ./config/manager/manager_image_patch.yaml
+If you want to deploy a released version of Gatekeeper in your cluster with a prebuilt image, then first copy the following kustomize configuration patch:
+
+  ```sh
+  cp config/manager/manager_image_patch.example.yaml config/manager/manager_image_patch.yaml
   ```
 
+Then modify the new manager_image_patch.yaml file to point to your prebuilt image. Finally, run the following:  
+
   ```sh
   kubectl apply -f https://raw.githubusercontent.com/open-policy-agent/gatekeeper/master/deploy/gatekeeper-constraint.yaml
   ```

config/manager/manager_image_patch.example.yaml → config/manager/manager_image_patch_template.yaml

@@ -1,3 +1,4 @@
+# You can copy this file to manager_image_patch.yaml to specify a prebuilt image
 apiVersion: apps/v1
 kind: StatefulSet
 metadata: