add note suggested by rhettinger about example.

Doc/lib/libhotshot.tex

@@ -96,6 +96,9 @@ of the \class{pstats.Stats} class.
 
 \subsection{Example Usage \label{hotshot-example}}
 
+Note that this example runs the python "benchmark" pystones. It can
+take some time to run, and will produce large output files.
+
 \begin{verbatim}
 
 >>> import hotshot, hotshot.stats, test.pystone