Fix typo

Change worker_directory to working_directory

Author: AndrewJo

.circleci/config.yml

@@ -5,7 +5,7 @@ jobs:
     machine:
       image: ubuntu-1604:201903-01
       docker_layer_caching: true
-    worker_directory: ~/docker-helm
+    working_directory: ~/docker-helm
     steps:
       - checkout
       - run: