add version tags

.drone.yml

@@ -27,19 +27,35 @@ steps:
   - npm install --prefix assets
   - mix test
 
-- name: build and publish
+- name: build and publish stable
   image: plugins/docker
   settings:
     repo: shibaobun/cannery
-    tags: latest
     username:
       from_secret: docker_username
     password:
       from_secret: docker_password
+    tags:
+      - latest
+      - ${DRONE_TAG}
   when:
     branch:
     - stable
 
+- name: build and publish tagged version
+  image: plugins/docker
+  settings:
+    repo: shibaobun/cannery
+    username:
+      from_secret: docker_username
+    password:
+      from_secret: docker_password
+    tags:
+      - ${DRONE_TAG}
+  when:
+    event:
+    - tag
+
 - name: rebuild-cache
   image: drillster/drone-volume-cache
   volumes: