[wwwdocs] readings.html link fix for PowerPC

[Gerald Pfeifer]

Fix link to The PowerPC architecture book.

Gerald

Index: readings.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/readings.html,v
retrieving revision 1.175
diff -u -3 -p -r1.175 readings.html
--- readings.html	3 May 2008 12:42:45 -0000	1.175
+++ readings.html	15 Jun 2008 09:07:40 -0000
@@ -230,7 +230,7 @@ Intel®64 and IA-32 Architectures Sof
   <br /><a href="http://publib16.boulder.ibm.com/pseries/en_US/infocenter/base/43_docs/aixassem/alangref/toc.htm">AIX V4.3 Assembler Language Ref.</a>
   <br /><a href="http://publibn.boulder.ibm.com/doc_link/en_US/a_doc_lib/aixassem/alangref/alangreftfrm.htm">AIX 5L Assembler Language Ref.</a>
   <br /><a href="http://www-128.ibm.com/developerworks/linux/library/l-powarch/">A developer's guide to the POWER architecture.</a>
-  <br /><a href="http://www-128.ibm.com/developerworks/eserver/articles/archguide.html">The PowerPC architecture book from IBM.</a>
+  <br /><a href="http://www.ibm.com/developerworks/eserver/library/es-archguide-v2.html">The PowerPC architecture book from IBM</a>
  </li>
  
  <li>sh