Cleaning up source.android.com files.

This change fixes some formatting artifacts that resulted from the export from
Sites, and also updates links to no longer point to Sites and use the standard
{@docRoot} idiom. Also contains a few content updates, and introduces a page
about branch management.

pdk/docs/source/source_toc.cs

@@ -25,6 +25,7 @@ function nothing() {}
     <li><a href="<?cs var:toroot ?>source/life-of-a-patch.html">Life of a Patch</a></li>
     <li><a href="<?cs var:toroot ?>source/submit-patches.html">Submitting Patches</a></li>
     <li><a href="<?cs var:toroot ?>source/report-bugs.html">Reporting Bugs</a></li>
+    <li><a href="<?cs var:toroot ?>source/code-lines.html">Branches &amp; Releases</a></li>
   </ul>
 </ul>