Update all generated readme auth instructions [(#1121)](https://github.com/GoogleCloudPlatform/python-docs-samples/issues/1121)
Update all generated readme auth instructions [(#1121)](https://github.com/GoogleCloudPlatform/python-docs-samples/issues/1121)

Change-Id: I03b5eaef8b17ac3dc3c0339fd2c7447bd3e11bd2
GoogleCloudPlatform/python-docs-samples,GoogleCloudPlatform/python-docs-samples,GoogleCloudPlatform/python-docs-samples,GoogleCloudPlatform/python-docs-samples