fix reference to File Object documentation

closes SF bug #825810

Doc/lib/libfuncs.tex

@@ -352,7 +352,9 @@ class C:
 \end{funcdesc}
 
 \begin{funcdesc}{file}{filename\optional{, mode\optional{, bufsize}}}
-  Return a new file object (described earlier under Built-in Types).
+  Return a new file object (described in
+  section~\ref{bltin-file-objects}, ``\ulink{File
+  Objects}{bltin-file-objects.html}'').
   The first two arguments are the same as for \code{stdio}'s
   \cfunction{fopen()}: \var{filename} is the file name to be opened,
   \var{mode} indicates how the file is to be opened: \code{'r'} for