update yaml example for SQS

pypubsub.yaml

@@ -35,4 +35,7 @@ clients:
 #    queue: myQueueName.fifo
 #    region: us-east-1
 #    delete: true  # If set, deletes items from SQS as they are processed. Comment out to keep items in SQS
+#    # The below can be commented out to use basic ~/.aws/credentials configuration for the user
+#    key: AWS_ACCESS_KEY_ID
+#    secret: AWS_SECRET_ACCESS_KEY