Updating the doc build file to include the new examples for Cells. Fixing the links in the associated JavaDoc.

Review at http://gwt-code-reviews.appspot.com/964801

Review by: fabbott@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@8958 8db76d5a-ed1c-0410-87a9-c151d255dfc7