Update "hosted by" in the intro

Despite its name, the front page of Readscheme.org is not specific to
Scheme. Linking to the Wayback Machine copy gives curious visitors an
opportunity browse it anyway.

www/index.html

@@ -36,19 +36,21 @@
           <p>
             This online bibliography collects together links to
             technical papers and theses related to the Scheme
-            language, including both classic papers and recent
+            language, including both classic papers and new
             research.
           </p>
           <p>
             This site was maintained by Jim Bender.
           </p>
           <p>
-            Readscheme.org was hosted by <a href=
+            This archival snapshot of library.readscheme.org is
-            "http://concurrency.cc">concurrency.cc</a>. This
+            hosted by the <a href=
-            archival snapshot of library.readscheme.org is hosted
-            at the <a href=
             "https://conservatory.scheme.org/">Scheme
-            Conservatory</a>.
+            Conservatory</a>. In the past, <a href=
+            "https://web.archive.org/web/20130614133107/http://readscheme.org/">
+            readscheme.org</a> has been hosted by <a href=
+            "http://www.untyped.com/">Untyped</a> and <a href=
+            "http://concurrency.cc">concurrency.cc</a>.
           </p>
           <h2>
             What's new...