Add Amazon OneLink

staging/index.html

@@ -87,4 +87,6 @@
 <p>Previous versions included a final Part on programming language semantics in particular.  I have decided to separate that part out.  I plan to put it up as a supplementary resource eventually; for now it is simply removed.  (It remains present in the <a href="repo">Mercurial</a> history.)</p>
 </div>
 
+<script src="//z-na.amazon-adsystem.com/widgets/onejs?MarketPlace=US&adInstanceId=14c7f9de-2f5e-4edd-af33-33d7e49e3296"></script>
+
 </body></html>