Add github action (#54)

Author: gxthrj

.github/workflows/linux_ci.yml

@@ -0,0 +1,15 @@
+name: Docker compose CI on linux
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: use docker-compose
+      run: cd ./example && docker-compose -p docker-apisix up -d