fix broken links in PDF
(SF patch #1281291, contributed by Rory Yorke)
diff --git a/Doc/ACKS b/Doc/ACKS
index 14a5ca8..bbb3241 100644
--- a/Doc/ACKS
+++ b/Doc/ACKS
@@ -195,6 +195,7 @@
 Steven Work
 Thomas Wouters
 Ka-Ping Yee
+Rory Yorke
 Moshe Zadka
 Milan Zamazal
 Cheng Zhang