Update README.md

README.md

@@ -55,7 +55,7 @@ Also, the latest commit-id should used in the code, so it should also be saved e
 ## 6. Containerization
 
 ## 7. CI/CD Pipeline with GitHub Actions
-In case no changes were made to Dockerfile or other files related to the docker-image:
+In case no changes were made to Dockerfile or the directory `/app`, no need to build the docker-image again, therefore:
 1. the workflow `docker_build` can be commented out as it takes around 10 minutes
 2. the previous commit-id should be used, i.e. line 85 should be commented out and the previous commit-id should be used as `DOCKER_IMAGE_TAG`, and line 88 should be commented.