Added docker workflows

.github/workflows/docker-image-dev.yml

@@ -0,0 +1,16 @@
+name: Docker Dev
+
+on:
+  push:
+    branches: [ dev-docker ]
+
+jobs:
+
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Build the Docker image
+      run: docker build . --file Dockerfile --tag my-image-name:$(date +%s)

.github/workflows/docker-image-pr.yml

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+name: DockerPR
+
+on:
+  pull_request:
+    branches: [ docker, dev-docker, alpha-docker ]
+
+jobs:
+
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Build the Docker image
+      run: docker build . --file Dockerfile --tag my-image-name:$(date +%s)

.github/workflows/docker-image-stable.yml

@@ -0,0 +1,16 @@
+name: Docker Stable
+
+on:
+  push:
+    branches: [ docker ]
+
+jobs:
+
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Build the Docker image
+      run: docker build . --file Dockerfile --tag my-image-name:$(date +%s)