Update storage-aws.md (#2992)

* Update storage-aws.md

Improve clarity around blocks vs chunks storage options.

* fix

Signed-off-by: Marco Pracucci <[email protected]>

* Fixed white noise

Signed-off-by: Marco Pracucci <[email protected]>

Co-authored-by: Marco Pracucci <[email protected]>

Author: amckinley

docs/production/storage-aws.md

@@ -18,8 +18,9 @@ if you use MFA), or use a short-term token solution such as
 
 ## Should I use S3 or DynamoDB ?
 
-Note that the choices are: "chunks" of timeseries data in S3 and index
-in DynamoDB, or everything in DynamoDB. Using just S3 is not an option.
+Note that the choices for the chunks storage backend are: "chunks" of
+timeseries data in S3 and index in DynamoDB, or everything in DynamoDB.
+Using just S3 is not an option, unless you use the [blocks storage](../../blocks-storage/) engine.
 
 Broadly S3 is much more expensive to read and write, while DynamoDB is
 much more expensive to store over months.  S3 charges differently, so