DOCSP-36620 passcode protection (#648)

* passcode protected step

Author: kyuan-mongodb

source/dashboards/dashboard-access/dashboard-permissions.txt

@@ -308,6 +308,23 @@ deployment who have a direct link:
       </reference/user-roles/#project-roles>` to access the data. To
       learn more about granting access, see :ref:`permission-model`.
 
+#. (Optional) Click :guilabel:`Protect this link with a passcode`.
+
+   |charts| generates a passcode to protect your dashboard. When users
+   try to view your public link, they must enter this passcode to view
+   your dashboard.
+
+   If you don't like the passcode that |charts| generates, or need to
+   change your passcode, click :guilabel:`Generate` for a new passcode.
+
+   If you uncheck :guilabel:`Protect this link with a passcode` and
+   click it again, |charts| generates a new passcode.
+
+   .. note::
+
+      After a user enters the passcode, the dashboard displays for five days unless they manually refresh the browser session.
+      After five days, users must sign in with the passcode again.
+
 #. Click :guilabel:`Close`. |charts| saves your changes automatically.
 
 .. warning:: Link Sharing with Sensitive Data