added note about selecting dataset

Author: kyuan-mongodb

source/atlas/sample-data.txt

@@ -58,6 +58,11 @@ Procedure
          :figwidth: 600px
          :alt: sample-data-load
 
+      .. note:: 
+
+         If Atlas prompts you to select which dataset to load, select
+         ``sample_guides``.
+
    .. step:: In the ensuing dialog, click :guilabel:`Load Sample Dataset` confirm.
 
       .. figure:: /images/sample-data-confirm-load.png