Update url.

Old url returned status code:301 Moved permanently.
diff --git a/Doc/lib/libzipimport.tex b/Doc/lib/libzipimport.tex
index 770ea21..098e788 100644
--- a/Doc/lib/libzipimport.tex
+++ b/Doc/lib/libzipimport.tex
@@ -50,9 +50,9 @@
 
 
 \begin{seealso}
-  \seetitle[http://www.pkware.com/appnote.html]{PKZIP Application
-            Note}{Documentation on the ZIP file format by Phil
-            Katz, the creator of the format and algorithms used.}
+  \seetitle[http://www.pkware.com/business_and_developers/developer/appnote/]
+           {PKZIP Application Note}{Documentation on the ZIP file format by
+            Phil Katz, the creator of the format and algorithms used.}
 
   \seepep{0273}{Import Modules from Zip Archives}{Written by James C.
           Ahlstrom, who also provided an implementation. Python 2.3