README.md in embulk-output-redshift-0.6.3 vs README.md in embulk-output-redshift-0.6.4

@@ -18,10 +18,10 @@
 - **database**: destination database name (string, required)
 - **schema**: destination schema name (string, default: "public")
 - **table**: destination table name (string, required)
 - **access_key_id**: access key id for AWS
 - **secret_access_key**: secret access key for AWS
-- **iam_user_name**: IAM user name for uploading temporary files to S3. The user should have permissions of `s3:GetObject`, `s3:PutObject`, `s3:DeleteObject`, , `s3:ListBucket` and `sts:GetFederationToken`. (string, default: "", but we strongly recommend that you use IAM user for security reasons. see below.)
+- **iam_user_name**: IAM user name for uploading temporary files to S3. The user should have permissions of `s3:GetObject`, `s3:PutObject`, `s3:DeleteObject`, `s3:ListBucket` and `sts:GetFederationToken`. And furthermore, the user should have permission of `s3:GetBucketLocation` if Redshift region and S3 bucket region are different. (string, default: "", but we strongly recommend that you use IAM user for security reasons. see below.)
 - **s3_bucket**: S3 bucket name for temporary files
 - **s3_key_prefix**: S3 key prefix for temporary files (string, default:"")
 - **options**: extra connection properties (hash, default: {})
 - **retry_limit** max retry count for database operations (integer, default: 12)
 - **retry_wait** initial retry wait time in milliseconds (integer, default: 1000 (1 second))