Making this action workflow more versatile

.github/workflows/build-docker.yml

@@ -34,6 +34,6 @@ jobs:
           file: ./contrib/docker/Dockerfile.apache
           platforms: linux/amd64,linux/arm64,linux/arm/v7
           push: true
-          tags: kovah/pixelfed-docker:latest
+          tags: ${{ secrets.DOCKER_HUB_ORGANISATION }}/pixelfed:latest
           cache-from: type=registry,ref=user/app:latest
           cache-to: type=inline