I created a Google Doc, and did the submission type as an External Tool and used the Google feature, and my student submitted an assignment, but it was done wrong. I want to allow him to submit it again, so I marked it as incomplete. But when he opens the assignment on his end, it just shows the .docx file, and nothing where he can edit what he submitted and submit it again. How do I allow him to resubmit an assignment? I see this page here, but it's not clear on how to enable resubmission.