improve readability for build-docker workflow

Signed-off-by: Markus Blaschke <[email protected]>

Author: mblaschke

.github/workflows/build-docker.yaml

@@ -61,7 +61,9 @@ jobs:
         id: docker_meta
         uses: docker/metadata-action@v5
         with:
-          images: ${{ github.repository }},quay.io/${{ github.repository }}
+          images: |
+            ${{ github.repository }}
+            quay.io/${{ github.repository }}
           labels: |
             io.artifacthub.package.readme-url=https://raw.githubusercontent.com/${{ github.repository }}/${{ github.event.repository.default_branch }}/README.md
           flavor: |