add docker build

.github/workflows/docker.yml

@@ -0,0 +1,24 @@
+name: Publish to Registry
+on:
+  release:
+    types: [published]
+  push:
+    branches:
+      - master
+  pull_request:
+    branches: [master]
+jobs:
+  update:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@master
+      - name: Get release version
+        id: get_version
+        run: echo ::set-env name=RELEASE_VERSION::$(echo ${GITHUB_REF:10})
+      - name: Publish to Registry
+        uses: elgohr/Publish-Docker-Github-Action@2.21
+        with:
+          name: oamdev/vela-core
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+          tags: "latest,${{ env.RELEASE_VERSION }}"