Add testing Dockerfile (#470)

* Add testing Dockerfile

* Add comments

* Format table

* Add tests/README.md

* Rephrase

* add note in dockerfile

.github/workflows/docker-build.yml

@@ -0,0 +1,26 @@
+name: docker
+
+on:
+  push:
+    branches:
+      - "master"
+
+jobs:
+  docker:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v2
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+      - name: Login to Docker Hub
+        uses: docker/login-action@v2
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+      - name: Build and push
+        uses: docker/build-push-action@v4
+        with:
+          push: true
+          platforms: linux/amd64,linux/arm64,linux/arm/v7
+          tags: ${{ secrets.DOCKERHUB_USERNAME }}/home-assistant-streamdeck-yaml:latest