code: protected Content getNavLinkIndex() {
          Content linkContent = getHyperLink(pathToRoot.resolve(
                  (configuration.splitindex
                      ? DocPaths.INDEX_FILES.resolve(DocPaths.indexN(1))
                      : DocPaths.INDEX_ALL)),
              indexLabel, "", "");
          Content li = HtmlTree.LI(linkContent);
          return li;
      }
docs: Get link for generated class index.
  
  @return a content tree for the link