Update user.rst

Author: jasonblais

source/guides/user.rst

@@ -18,6 +18,7 @@ Getting Started
    /help/getting-started/creating-teams.md
    /help/getting-started/managing-members.md
    /help/getting-started/organizing.rst
+   /help/apps/desktop-guide.rst
 
 Messaging
 =========