I would tell them what they need to know, but no more than that, in case you broke any rules by reading the document. They don't need to know how you know, and

I would tell them what they need to know, but no more than that, in case you broke any rules by reading the document. They don't need to know how you know, and in fact no more than one person even needs to know that it came from you. Additionally, they don't need to know exactly when you found out. Getting a head start on finding a job first is not unfair in this case - anyone looking for a job is competing with other people, and there's nothing wrong with using your good luck to your advantage in that competition. Just be reasonable. Really, everyone in the tech industry should have a plan for this though, imo.