DOCSP-34755 Add Connection String Option Note (#74)

* DOCSP-34755 Add Connection String Option Note

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* *

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Author: ianf-mongodb

source/connection-strings/mongodb-database-connection-strings.txt

@@ -19,8 +19,17 @@ the procedure to make an authenticated user account and the Uniform Resource
 Identifier (URI) formats for defining connections to your target 
 MongoDB database. 
 
-Relational Migrator can use both Atlas and on-premises URIs. This page 
-provides separate instructions for each deployment type.
+About this Task
+---------------
+
+- Relational Migrator supports all connection string options except 
+  :urioption:`appName`. Relational Migrator overrides the ``appName`` 
+  connection string option when connecting to your MongoDB deployment. 
+  For details on MongoDB connection string options, see 
+  :ref:`<mongodb-uri>`.
+
+- Relational Migrator can use both Atlas and on-premises URIs. This page 
+  provides separate instructions for each deployment type.
 
 Atlas
 -----