DOC-6760: Add a Note for the DataSource sslmode property in the Insta…

…ll Ubuntu page (#7492)

Co-authored-by: Carrie Warner (Mattermost) <[email protected]>

source/install/install-ubuntu.rst

@@ -121,6 +121,10 @@ Verify that Mattermost is running: curl ``http://localhost:8065``. You should se
 
 The final step, depending on your requirements, is to run ``sudo systemctl enable mattermost.service`` so that Mattermost will start on system boot.
 
+.. note::
+
+	The value of the ``sslmode`` property in the ``DataSource`` configuration is entirely dependent on your native environment. Please consult the native environment setup documentation for guidance on its value. The available options for ``sslmode`` are ``disable`` or ``require``. For example, if you are using Amazon Lightsail as your data source, you must set ``sslmode`` to ``require`` to successfully connect to the database.
+
 Updates
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