This is the policy used for https://medium.com/tensult/make-a-website-dynamic-using-apis-f5d07def5d77

dynamodb-permissions-policy.json

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "mywebsiteContactUsTableWrite",
            "Effect": "Allow",
            "Action": [
                "dynamodb:PutItem",
                "dynamodb:UpdateItem"
            ],
            "Resource": [
                "arn:aws:dynamodb:*:*:table/mywebsite-contact-us"
            ]
        }
    ]
 }