There was a phishing email going through Gmail earlier today, and Google pretty much solved the problem, but… Here’s some thoughts.
Don’t open it. It is from email@example.com, and looks like someone is sharing a document with you. They’re not.
If you already opened it, change your password ASAP.
Also go here: https://myaccount.google.com/permissions and remove permissions for “Google Docs” if it appears there. This is a really well-done phishing attack.