Added instructions for configuring an S3 dataset.

      location: /data/cordex

```

## Using S3 buckets for data

An S3 location for a dataset can be specified using `s3Location` instead of `location` in the yaml config, e.g.:

```yaml

  datasets:

    - name: CMIP6

      path: esg_cmip6

      s3Location:

        host: example.com

        port: 443

        bucket: bucket_name

        dataPath: path/to/files

```

We don't currently support adding security parameters for accessing secured S3 buckets.

## Fowarding access logs

The THREDDS and Nginx file server components can be configured to forward access logs to