code: protected void addAllModulesLink(Content ul) {
          Content linkContent = getHyperLink(DocPaths.MODULE_OVERVIEW_FRAME,
                  contents.allModulesLabel, "", "packageListFrame");
          Content li = HtmlTree.LI(linkContent);
          ul.addContent(li);
      }
docs: Adds "All Modules" link for the top of the left-hand frame page to the
  documentation tree.
  
  @param ul the Content object to which the all modules link should be added