Add documentation and cloudformation to include creating policy

[andrewkrug]

This is a low priority. I just want to capture it.

Since we have a custom policy for execution we should give users a way to provision that themselves.

[andrewkrug]

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "logs:CreateLogGroup",
                "logs:CreateLogStream",
                "logs:PutLogEvents"
            ],
            "Resource": "arn:aws:logs:*:*:*"
        },
        {
            "Effect": "Allow",
            "Action": [
                "s3:PutObject"
            ],
            "Resource": "arn:aws:s3:::threatresponse.showdown*"
        }
    ]
}

[andrewkrug]

low priority