feat: first build testing

- add README
- update build steps to use docker.sock

.drone.yml

@@ -25,6 +25,9 @@ steps:
     when:
       branch:
         - master
+      event:
+        - push
+
     commands:
       - apk add --no-cache make bash git
       - echo "$DOCKER_PASSWORD" | docker login --username=$DOCKER_USERNAME --password-stdin git.query.consul