Updated creds help to explain how things work under gcloud vs standalone distro
Updated creds help to explain how things work under gcloud vs standalone distro

GoogleCloudPlatform/gsutil,craigcitro/gsutil,GoogleCloudPlatform/gsutil,dimfeld/gsutil,mattdr/gsutil,chriskuehl/gsutil-debian,ttiurani/gsutil,fishjord/gsutil,dtjackson/gsutil,BrandonY/gsutil