Create docker-image.yml

Automatically push new releases to Docker.

.github/workflows/docker-image.yml

@@ -0,0 +1,24 @@
+name: Docker Image Build
+
+on:
+  release:
+    types: [published]
+
+jobs:
+  build-release:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+
+      - name: Login to DockerHub
+        uses: docker/login-action@v1
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Build and push image 
+        uses: docker/build-push-action@v2
+        with:
+          push: true
+          tags: jokkedk/webgrind:latest