Pin sample app tag

Author: niallthomson

website/docs/automation/gitops/flux/ci.md

@@ -19,6 +19,7 @@ Next, populate the CodeCommit repository with the sources from the public reposi
 
 ```bash
 $ git clone https://github.com/aws-containers/retail-store-sample-app ~/environment/retail-store-sample-app
+$ git -C ~/environment/retail-store-sample-app checkout 0.4.0
 $ git -C ~/environment/retail-store-sample-codecommit checkout -b main
 $ cp -R ~/environment/retail-store-sample-app/src ~/environment/retail-store-sample-codecommit
 ```