Add note on the relationship between OUTPUT_PATH and terraform_root in the README (#686)
Add note on the relationship between OUTPUT_PATH and terraform_root in the README (#686)

* Update README

Co-authored-by: Xin Gao <ddeaf9d7b96265023645b8a66c7922693b2c3d37@users.noreply.github.com>
GoogleCloudPlatform/solution-acceleration-toolkit,GoogleCloudPlatform/solution-acceleration-toolkit