Bump AMD64 from Tier-3 (experimental) to Tier-2.

In reality, it is pretty close to Tier-1, but there are still a few
loose ends that need to be taken care of before locking down ABIs etc.
It was actually included in 5.1-RELEASE and it now has pre-built ports
packages etc.

en_US.ISO8859-1/articles/committers-guide/article.sgml

@@ -607,11 +607,11 @@
 	</itemizedlist>
 
 	<para>You will almost certainly get a conflict because
-	  of the <literal>$Id: article.sgml,v 1.167 2003-06-30 18:34:41 ceri Exp $</literal> (or in FreeBSD's case,
+	  of the <literal>$Id: article.sgml,v 1.168 2003-07-12 01:04:23 peter Exp $</literal> (or in FreeBSD's case,
 	  <literal>$<!-- stop expansion -->FreeBSD<!-- stop expansion -->$</literal>)
 	  lines, so you will have to edit the file to resolve the conflict
-	  (remove the marker lines and the second <literal>$Id: article.sgml,v 1.167 2003-06-30 18:34:41 ceri Exp $</literal> line,
-	  leaving the original <literal>$Id: article.sgml,v 1.167 2003-06-30 18:34:41 ceri Exp $</literal> line intact).</para>
+	  (remove the marker lines and the second <literal>$Id: article.sgml,v 1.168 2003-07-12 01:04:23 peter Exp $</literal> line,
+	  leaving the original <literal>$Id: article.sgml,v 1.168 2003-07-12 01:04:23 peter Exp $</literal> line intact).</para>
       </listitem>
 
       <listitem>
@@ -2082,7 +2082,7 @@ docs:Documentation Bug:freebsd-doc:</programlisting>
 	2 status as the availability of resources to continue to maintain
 	the system in a Production Quality state diminishes.</para>
 
-      <para>Current Tier 2 platforms are PowerPC and ia64.</para>
+      <para>Current Tier 2 platforms are PowerPC, ia64 and AMD64.</para>
     </sect2>
 
     <sect2>
@@ -2102,7 +2102,7 @@ docs:Documentation Bug:freebsd-doc:</programlisting>
 	providing source control and easier change integration from the
 	main FreeBSD tree.</para>
 
-      <para>Current Tier 3 platforms are S/390 and x86-64.</para>
+      <para>Current Tier 3 platforms are S/390.</para>
     </sect2>
 
     <sect2>