[skip ci] Update README, add skip ci support for workflow

.forgejo/workflows/build.yaml

@@ -1,17 +1,23 @@
+name: Build Docker image
+
 on:
   push:
   schedule:
     - cron: "0 12 * * *"
+
 jobs:
   build_image:
     name: Build image
+    runs-on: docker
+    if: env.SCHEDULED == 'true' || !contains(github.event.commits[0].message, '[skip ci]')
+
     env:
       VERSION: 22.04
       SCHEDULED: ${{ github.event_name == 'schedule' }}
       PUSHED: ${{ github.event_name == 'push' }}
       REGISTRY: git.korhonen.cc
       REPO: ${{ env.REGISTRY }}/functionalhacker/ubuntu-act
-    runs-on: docker
+
     steps:
       - name: Check if update available
         if: env.SCHEDULED == 'true'
@@ -20,12 +26,15 @@ jobs:
         with:
           base-image: docker://ghcr.io/catthehacker/ubuntu:act-${{ env.VERSION }}
           derived-image: docker://${{ env.REPO }}:latest
+
       - name: Check result
         if: env.SCHEDULED == 'true'
         run: echo "Needs updating = ${{ steps.check.outputs.differs }}"
+
       - name: Set up Docker Buildx
         if: env.PUSHED == 'true' || steps.check.outputs.differs == 'true'
         uses: docker/setup-buildx-action@v3
+
       - name: Login to Docker registry
         if: env.PUSHED == 'true' || steps.check.outputs.differs == 'true'
         uses: docker/login-action@v3
@@ -33,6 +42,7 @@ jobs:
           registry: ${{ env.REGISTRY }}
           username: ${{ secrets.REGISTRY_USER }}
           password: ${{ secrets.REGISTRY_PASSWORD }}
+
       - name: Build and push image
         if: env.PUSHED == 'true' || steps.check.outputs.differs == 'true'
         uses: docker/build-push-action@v5

README.adoc

@@ -4,4 +4,4 @@ Based on the link:https://github.com/catthehacker/docker_images[ghcr.io/cattheha
 
 * link:https://github.com/containers/skopeo[skopeo]
 
-Image is built at 12:00 EET every day if upstream updates are available.
+Image is built at 12:00 EET/EEST every day if upstream updates are available.