Add info about fetching credentials from IAM role
Fixes
@@ -20,10 +20,10 @@ Amazon S3 or S3 compatible services for object storage.
<code>accesskey</code>
</td>
<td>
- yes
+ no
</td>
<td>
- Your AWS Access Key.
+ Your AWS Access Key. If you use [IAM roles](http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/iam-roles-for-amazon-ec2.html), omit to fetch temporary credentials from IAM.
</td>
</tr>
<tr>
@@ -31,10 +31,10 @@ Amazon S3 or S3 compatible services for object storage.
<code>secretkey</code>
</td>
<td>
- yes
+ no
</td>
<td>
- Your AWS Secret Key.
+ Your AWS Secret Key. If you use [IAM roles](http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/iam-roles-for-amazon-ec2.html), omit to fetch temporary credentials from IAM.
</td>
</tr>
<tr>
@@ -160,7 +160,10 @@ Amazon S3 or S3 compatible services for object storage.
`secretkey`: Your aws secret key.
-**Note** You can provide empty strings for your access and secret keys if you plan on running the driver on an ec2 instance and will handle authentication with the instance's credentials.
+> **Note** You can provide empty strings for your access and secret keys to run the driver
+> on an ec2 instance and will handle authentication with the instance's credentials. If you
+> use [IAM roles](http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/iam-roles-for-amazon-ec2.html),
+> omit these keys to fetch temporary credentials from IAM.
`region`: The name of the aws region in which you would like to store objects (for example `us-east-1`). For a list of regions, you can look at http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-regions-availability-zones.html
