[css-syntax] Add a Previous Version link.

Author: SimonSapin

css-syntax/Overview.html

@@ -13,7 +13,7 @@
   <h1 class="p-name no-ref" id=title>CSS Syntax Module Level 3</h1>
   <h2 class="no-num no-toc no-ref" id=subtitle><span class=content>Editor's Draft,
     <span class=dt-updated><span class=value-title title=20130814>14 August 2013</span></span></span></h2>
-  <div data-fill-with=spec-metadata><dl><dt>This version:<dd><a class=u-url href=http://dev.w3.org/csswg/css-syntax>http://dev.w3.org/csswg/css-syntax</a><dt>Editor's Draft:<dd><a href=http://dev.w3.org/csswg/css-syntax>http://dev.w3.org/csswg/css-syntax</a>
+  <div data-fill-with=spec-metadata><dl><dt>This version:<dd><a class=u-url href=http://dev.w3.org/csswg/css-syntax>http://dev.w3.org/csswg/css-syntax</a><dt>Editor's Draft:<dd><a href=http://dev.w3.org/csswg/css-syntax>http://dev.w3.org/csswg/css-syntax</a><dt>Previous Versions:<dd><a href=http://www.w3.org/TR/2003/WD-css3-syntax-20030813/ rel=previous>http://www.w3.org/TR/2003/WD-css3-syntax-20030813/</a>
 <dt>Feedback:</dt>
     <dd><a href="mailto:www-style@w3.org?subject=%5Bcss-syntax%5D%20feedback">www-style@w3.org</a>
         with subject line

css-syntax/Overview.src.html

@@ -3,6 +3,7 @@ <h1>CSS Syntax Module Level 3</h1>
 <pre class='metadata'>
 Status: ED
 ED: http://dev.w3.org/csswg/css-syntax
+Previous Version: http://www.w3.org/TR/2003/WD-css3-syntax-20030813/
 Shortname: css-syntax
 Level: 3
 Editor: Tab Atkins Jr., Google, http://xanthir.com/contact/