Define NAA acronym at first mention (#4968)

Author: AlexJerabek

docs/develop/enable-nested-app-authentication-in-your-add-in.md

@@ -1,14 +1,14 @@
 ---
-title: Enable SSO in an Office Add-in using nested app authentication
-description: Learn how to enable SSO in an Office Add-in using nested app authentication.
-ms.date: 12/18/2024
+title: Enable single sign-on in an Office Add-in with nested app authentication
+description: Learn how to enable SSO in an Office Add-in with nested app authentication.
+ms.date: 12/23/2024
 ms.topic: how-to
 ms.localizationpriority: high
 ---
 
-# Enable SSO in an Office Add-in using nested app authentication
+# Enable single sign-on in an Office Add-in with nested app authentication
 
-You can use the MSAL.js library with nested app authentication to use SSO from your Office Add-in. Using nested app authentication offers several advantages over the On-Behalf-Of (OBO) flow.
+You can use the MSAL.js library with nested app authentication to use single sign-on (SSO) from your Office Add-in. Using nested app authentication (NAA) offers several advantages over the On-Behalf-Of (OBO) flow.
 
 - You only need to use the MSAL.js library and don’t need the `getAccessToken` function in Office.js.
 - You can call services such as Microsoft Graph with an access token from your client code as an SPA. There’s no need for a middle-tier server.