(DOCSP-18432): Backport DOCSP-17931 to v5.0. (mongodb#5755)

* (DOCSP-17931): Added Atlas connection string note.

* (DOCSP-17931): Incorporated Jeff's feedback.

* (DOCSP-17931): Incorporated Jeff's feedback.

* (DOCSP-17931): Incorporated JD's feedback.

Author: corryroot

source/reference/connection-string.txt

@@ -122,6 +122,25 @@ Examples
 
              .. include:: /includes/fact-pct-encode-uri.rst
 
+      - id: atlas
+        name: Atlas Deployment
+        content: |
+
+           MongoDB Atlas provides the connection strings for 
+           your deployment when you click the :atlas:`Connect
+           </connect-to-database-deployment/>` button in the Atlas UI. 
+           To register a new Atlas account, start at the 
+           :mdbacct:`MongoDB Atlas registration page 
+           </register?tck=docs_server>`. To learn more, see
+           :atlas:`Get Started with Atlas </getting-started/>`.
+
+           Your Atlas connection string might resemble the following 
+           example:
+
+           .. code-block:: bash
+
+              mongosh "mongodb+srv://cluster0.example.mongodb.net myFirstDatabase" --username JohnDoe
+
 For more examples, see :ref:`connections-connection-examples`.
 
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