Add some relevant <link> elements.

Doc/html/about.html

@@ -5,6 +5,8 @@
     <meta name="description"
       content="Overview information about the Python documentation">
     <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
+    <link rel="contents" href="index.html" title="Python Documentation Index">
+    <link rel="index" href="modindex.html" title="Global Module Index">
     <link rel="SHORTCUT ICON" href="icons/pyfav.gif" type="image/gif">
     <link rel="STYLESHEET" href="lib/lib.css">
   </head>

Doc/html/index.html.in

@@ -7,6 +7,9 @@
                    Python @RELEASE@.">
     <link rel="SHORTCUT ICON" href="icons/pyfav.gif" type="image/gif">
     <link rel="STYLESHEET" href="lib/lib.css" type="text/css">
+    <link rel="author" href="acks.html" title="Acknowledgements">
+    <link rel="help" href="about.html" title="About the Python Documentation">
+    <link rel="index" href="modindex.html" title="Global Module Index">
     <style type="text/css">
       a.title { font-weight: bold; font-size: 110%; }
       ul { margin-left: 1em; padding: 0pt; border: 0pt; }