add index entry

Doc/mac/libmacui.tex

@@ -143,6 +143,7 @@ cancel button,
 \class{unicode}, \class{FSSpec}, \class{FSRef} and subtypes thereof are
 acceptable.
 
+\index{Navigation Services}
 For a description of the other arguments please see the Apple Navigation
 Services documentation and the \module{EasyDialogs} source code.
 \end{funcdesc}