Replace the XXX marker in the 'Arrays and pointers' reference manual

section with a link to the tutorial sections.

Backported from trunk.

Doc/lib/libctypes.tex

@@ -2440,5 +2440,6 @@ attributes for names not present in \member{{\_}fields{\_}}.
 
 \subsubsection{Arrays and pointers\label{ctypes-arrays-pointers}}
 
-XXX
+Not yet written - please see section~\ref{ctypes-pointers}, pointers and
+section~\ref{ctypes-arrays}, arrays in the tutorial.