Added docker build to drone ci config

.drone.yml

@@ -7,5 +7,16 @@ steps:
     image: node:16-alpine
     commands:
       - yarn install
-      - yarn test-build
+      - yarn lint
-      - yarn lint
+      - yarn build
+
+  - name: build docker file and push to docker hub
+    image: plugins/docker
+    pull: never
+    settings:
+      repo: guusvanmeerveld/portfolio
+      tags: latest
+      username:
+        from_secret: docker_username
+      password:
+        from_secret: docker_password