Refactor .drone.yml and add notification

.drone.yml

@@ -1,16 +1,18 @@
-pipeline:
-  build:
+kind: pipeline
+name: default
+
+steps:
+  - name: build
     image: ruby
     commands:
       - gem install bundler
       - bundle install
       - bundle exec jekyll build
   
-  docker:
+  - name: docker
     image: plugins/docker
     repo: docker.data.coop/data-coop-website
     registry: docker.data.coop
-    secrets: [DOCKER_USERNAME, DOCKER_PASSWORD]
     username:
       from_secret: DOCKER_USERNAME
     password:
@@ -21,3 +23,13 @@ pipeline:
     when:
       branch:
         - master
+
+  - name: notify
+    image: plugins/matrix
+    settings:
+      homeserver: https://data.coop
+      roomid: plKSghHbepWeUEtbHE:data.coop
+      username:
+        from_secret: matrix_username
+      password:
+        from_secret: matrix_password