Added action to push to dockerhub

.github/workflows/docker.yml

@@ -0,0 +1,19 @@
+name: Docker
+
+on:
+  push:
+    branches: [ master ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: 'Checkout GitHub Action'
+        uses: actions/checkout@v2
+      - name: Build and push docker
+        uses: docker/build-push-action@v1
+        with:
+          username: ${{ secrets.REGISTRY_USERNAME }}
+          password: ${{ secrets.REGISTRY_PASSWORD }}
+          repository: DOCKER_REPOSITORY
+          tags: latest