Misc. minor doc improvements (mostly new links).

chrome/common/extensions/docs/static/docs.html

 <div id="pageData-name" class="pageData">Hello There!</div>
 
 <p>
 This documentation tells you how to write extensions
 and packaged apps for the
 <a href="http://www.google.com/chrome">Google Chrome browser</a>.
 Because extensions came first,
 the APIs and these docs say <em>extension</em> everywhere.
 </p>
 
@@ skipping 105 matching lines @@
       APIs on the Dev channel are subject to change.
       </p>
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   <tr>
     <td>
       <a href="http://code.google.com/chrome/extensions/trunk/overview.html">.../extensions/<b>trunk/</b>...</a>
     </td>
     <td>
       The very latest documentation.
-      Look here if you're using a tip-of-tree version of
+      Look here if you're using
+      <a href="http://tools.google.com/dlpage/chromesxs">Canary</a>
+      or a tip-of-tree version of
       <a href="http://dev.chromium.org">Chromium</a>
       or if you're curious about features to come.
       This version might also have bug fixes and feature information
       that are relevant to the current doc
       but haven't been integrated into it yet.
 
       <p>
       <strong>Note:</strong>
       The trunk version of the doc is preliminary and might have errors.
       </p>
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 </table>
 </p>