Add a publish workflow and edit the README file

.github/workflows/publish-container.yml

@@ -0,0 +1,43 @@
+name: Publish container image
+
+on:
+  push:
+    branches:
+      - 'main'
+    tags:
+      - 'v*'
+
+jobs:
+  build-and-push-image:
+    runs-on: ubuntu-latest
+    permissions: 
+      contents: read
+      packages: write
+
+    steps:
+      - name: Aquire code
+        if: always()
+        uses: actions/checkout@v2
+      - name: Log into ghcr.io
+        uses: docker/login-action@v2
+        with:
+            registry: ghcr.io
+            username: ${{ github.actor }}
+            password: ${{ secrets.GITHUB_TOKEN }}
+      - name: Get metadata
+        id: meta
+        uses: docker/metadata-action@v4
+        with:
+          images: |
+            ghcr.io/mini-bomba/create-github-release
+          tags: |
+            type=ref,event=branch
+            type=semver,pattern={{raw}}
+            type=sha,prefix=,suffix=,format=short
+      - name: Build & push image
+        uses: docker/build-push-action@v3
+        with:
+          context: .
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}

Dockerfile

@@ -1,4 +1,5 @@
 FROM python:3.9.6-slim-buster
+LABEL org.opencontainers.image.source=https://github.com/mini-bomba/create-github-release
 
 # Install git
 RUN apt-get update && apt-get install git -y --no-install-recommends

README.md

@@ -73,7 +73,7 @@ jobs:
     # would go here
     #
       - name: Release the new binaries
-        uses: mini-bomba/create-github-release@v1.0.0
+        uses: mini-bomba/create-github-release@v1.1.0
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
           tag: "latest"
@@ -89,4 +89,23 @@ jobs:
             build/*.exe
           clear_attachments: true
 ```
+## Using the ghcr.io image instead of building on demand
+I provide automatically-built docker images via Gihub Packages, which are compatible with any workflows using the action.
+If my action takes too long to build on demand for you, or if you have issues with multiple copies cluttering up your
+selfhosted runner's disk space, you can use the prebuilt images instead.
 
+To replace the action with the prebuilt image, simply replace
+```yaml
+uses: mini-bomba/[email protected]
+```
+with
+```yaml
+uses: docker://ghcr.io/mini-bomba/[email protected]
+```
+in your workflows.
+
+The images are built for any version tag and any commit on the main branch.
+Note that commit images are tagged with the first 7 characters of the commit hash.
+See the package page for more info.
+
+The images should work in the same way as the action, no further changes to the workflow should be required.