UI: Clarify and improve locale text

Renaming it to prevent possible confusion with the source context
toolbar.

UI/data/locale/en-US.ini

@@ -594,7 +594,7 @@ Basic.MainMenu.View.Docks="Docks"
 Basic.MainMenu.View.Docks.ResetUI="Reset UI"
 Basic.MainMenu.View.Docks.LockUI="Lock UI"
 Basic.MainMenu.View.Docks.CustomBrowserDocks="Custom Browser Docks..."
-Basic.MainMenu.View.ListboxToolbars="&Listbox Toolbars"
+Basic.MainMenu.View.ListboxToolbars="Scene/Source List Buttons"
 Basic.MainMenu.View.SceneTransitions="S&cene Transitions"
 Basic.MainMenu.View.SourceIcons="Source &Icons"
 Basic.MainMenu.View.StatusBar="&Status Bar"