DOCSP-34873 Allow manual cluster namespace input (#294)

* DOCSP-34873 Allow manual cluster namespace input

* DOCSP-34873 updates for HC's feedback

* DOCSP-34873 updates for CR feedback

Author: kanchana-mongodb

source/tutorial/add-dataset-pipeline.txt

@@ -99,15 +99,23 @@ Procedure
                   |service| cluster where you loaded the sample data.
 
             #. Select the database on the specified cluster from the 
-               dropdown.
+               dropdown, or type the database name in the field if the
+               database isn't listed in the dropdown.
+
+               {+adl+} won't display the database if it's unable to
+               fetch the names of the databases for the specified cluster. 
 
                .. example:: 
 
                   If you selected the cluster where the sample data is 
                   loaded, select ``sample_mflix``. 
 
             #. Select the collection in the specified database from the 
-               dropdown.
+               dropdown, or type the collection name in the field if the
+               collection isn't available.
+
+               {+adl+} won't display the collection if it's unable to
+               fetch the collection namespace for the specified cluster. 
 
                {+adl+} doesn't support :manual:`Views </core/views/>` as a
                data source for pipelines. You must select a collection from
@@ -201,7 +209,9 @@ Procedure
             .. include:: /includes/list-table-supported-aws-regions.rst
 
             By default, {+adl+} automatically selects the region closest to 
-            your |service| cluster for storing extracted data. 
+            your |service| cluster for storing extracted data. If
+            {+adl+} is unable to determine the region, it defaults to
+            ``us-east-1``. 
 
          .. step:: Specify fields in your collection to create partitions.