doc(src/install-deis/configuring-object-storage.md): clarifying the given S3 URL

Author: Aaron Schlesinger

src/installing-deis/configuring-object-storage.md

@@ -19,7 +19,7 @@ Additionally, Deis ships with a [Minio](http://minio.io) [component](https://git
 The Deis components determine what object storage system to use via environment variables that you set up. The below list is the lookup order for all Deis components.
 
 - `DEIS_OUTSIDE_STORAGE` - The external S3-compatible object storage system. Commonly used URLs:
-  - `s3.amazonaws.com` for Amazon S3
+  - `s3.amazonaws.com` for Amazon S3's `us-east-1a` region
   - `storage.googleapis.com` for Google Cloud Storage
 - `DEIS_MINIO_SERVICE_HOST` and `DEIS_MINIO_SERVICE_PORT` - The in-cluster Minio service. Note that these will be set automatically by Kubernetes if you run [Minio](http://minio.io) as a service in the cluster. See [the Minio service from the Deis Minio Chart](https://github.com/deis/charts/blob/master/deis-dev/manifests/deis-minio-service.yaml) for an example service.