helm: Add link or rationale to `[build.Tag] is not used. [build.ImageName] is used instead` message

My helm deploy works fine, but after helm dumps out the status of all generated pods that were deployed successfully, i get this message.

```
WARN[0079] image [dockerhub.mydomain.com/hhd/my-app:4f205e7-dirty@sha256:67285744c3d0e23e95bc318869f538794a73891cc0b4335b5a5ea6670b042fc5] is not used.
WARN[0079] image [dockerhub.mydomain.com/hhd/my-app] is used instead.
WARN[0079] See helm sample for how to replace image names with their actual tags: https://github.com/GoogleContainerTools/skaffold/blob/master/examples/helm-deployment/skaffold.yaml
```

If I describe my pod I see that it is indeed using the image `dockerhub.mydomain.com/hhd/my-app:4f205e7-dirty`..... so I don't get whats wrong.

Also this link provides no useful information:

```
WARN[0079] See helm sample for how to replace image names with their actual tags: https://github.com/GoogleContainerTools/skaffold/blob/master/examples/helm-deployment/skaffold.yaml
```