add prerelease flag

Author: mongoKart

source/quick-start.txt

@@ -84,7 +84,12 @@ Set Up Your Project
 
       .. code-block:: shell
 
-         dotnet add package {+package+} 
+         dotnet add package {+package+} --prerelease
+      
+      .. note:: Prerelease Flag
+
+         You must include the ``--prerelease`` flag to install the prerelease
+         version of the {+package+} package.
 
 Query Your MongoDB Cluster from Your Application
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