Fixing workflow tag syntax issues

.github/workflows/containers.yml

@@ -1,10 +1,12 @@
 name: Build and push containers
 
 on:
+  # Automatically triggered by a testing workflow passing
   workflow_run:
     workflows: ["ChangeDetection.io Test"]
     types: [completed]
 
+  # Or a new tagged release
   release:
     types: [created, published, edited]
 
@@ -26,6 +28,8 @@ jobs:
 
   on-success:
     runs-on: ubuntu-latest
+    # If the testing workflow has a success, then we build to :latest
+    # Or if we are in a tagged release scenario.
     if: ${{ github.event.workflow_run.conclusion == 'success' }} || ${{ github.event.release.tag_name }} != ''
     steps:
       - uses: actions/checkout@v2
@@ -74,6 +78,7 @@ jobs:
           version: latest
           driver-opts: image=moby/buildkit:master
 
+      # master always builds :latest
       - name: Build and push :latest
         id: docker_build
         if: ${{ github.ref == 'refs/heads/master'}}
@@ -89,17 +94,18 @@ jobs:
           cache-from: type=local,src=/tmp/.buildx-cache
           cache-to: type=local,dest=/tmp/.buildx-cache
 
+      # A new tagged release is required, which builds :tag
       - name: Build and push :tag
         id: docker_build_tag_release
-        if: startsWith(github.ref, 'refs/tags/')
+        if: ${{ github.event.release.tag_name }} != ''
         uses: docker/build-push-action@v2
         with:
           context: ./
           file: ./Dockerfile
           push: true
           tags: |
-            ${{ secrets.DOCKER_HUB_USERNAME }}/changedetection.io:${{ steps.tagName.outputs.tag }}
-            ghcr.io/dgtlmoon/changedetection.io:${{ steps.tagName.outputs.tag }}
+            ${{ secrets.DOCKER_HUB_USERNAME }}/changedetection.io:${{ github.event.release.tag_name }}
+            ghcr.io/dgtlmoon/changedetection.io:${{ github.event.release.tag_name }}
           platforms: linux/amd64,linux/arm64,linux/arm/v6,linux/arm/v7
           cache-from: type=local,src=/tmp/.buildx-cache
           cache-to: type=local,dest=/tmp/.buildx-cache