Cloud Config: Documentation says to make Docker registry public.

I am following the steps to set up a cloud project to run fuzzbench, and [the docs say](https://google.github.io/fuzzbench/running-a-cloud-experiment/setting-up-a-google-cloud-project/#dispatcher-image-and-container-registry-setup) that I should make my docker registry public. Is that required? I would prefer to keep my docker images private and accessible only for the people from my organization.