Replace to XXX notes to add references with real references.

Doc/lib/libzipfile.tex

@@ -65,8 +65,13 @@ The available attributes of this module are:
 
 
 \begin{seealso}
-  \seetext{XXX point to ZIP format definition}
-  \seetext{XXX point to Info-ZIP home page; mention WiZ}
+  \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.info-zip.org/pub/infozip/]{Info-ZIP Home Page}{
+            Information about the Info-ZIP project's ZIP archive
+            programs and development libraries.}
 \end{seealso}