adding note about circleci example and puts

circle_ci/5-custom-transformers.md

@@ -125,6 +125,12 @@ transform "codecov_codecov_upload" do |item|
 end
 ```
 
+In this case, `puts` will only print `{}` to the console since there are no properties of the CircleCI step. In the source configuration, it simply appears as:
+
+```yml
+- codecov/upload
+```
+
 ## Custom transformers for environment variables
 
 You can use custom transformers to edit the values of environment variables in converted workflows. In this example, you will update the `COVERAGE_DIR` environment variable to be `$RUNNER_TEMP/cov` instead of `./tmp/cov`.