Update README.md

[megalucio]

in the provided example, output_cloud_storage is not a valid input, it should be output_storage

[google-cla[bot]]

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[mikouaj]

Thank you @megalucio for opening this pull request! Can you please go to https://cla.developers.google.com and sign the Contributor License Agreement so we can have it merged?

[mikouaj]

Stale, closing this PR