Minimal IAM policy for the resolver

[laughedelic]

Following @benoahriz's question on gitter, I'm going to add documentation about minimal needed IAM permissions for resolving/publishing.

Here is an example policy:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "s3:CreateBucket",
                "s3:ListBucket"
            ],
            "Resource": "arn:aws:s3:::bucket.name"
        },
        {
            "Effect": "Allow",
            "Action": [
                "s3:PutObject",
                "s3:PutObjectAcl",
                "s3:GetObject"
            ],
            "Resource": "arn:aws:s3:::bucket.name/*"
        }
    ]
}

[laughedelic]

Closed by #43