code: protected Content getPackage(PackageDoc pd) {
          Content packageLinkContent;
          Content packageLabel;
          if (pd.name().length() > 0) {
              packageLabel = getPackageLabel(pd.name());
              packageLinkContent = getHyperLink(pathString(pd,
                       DocPaths.PACKAGE_FRAME), packageLabel, "",
                      "packageFrame");
          } else {
              packageLabel = new StringContent("<unnamed package>");
              packageLinkContent = getHyperLink(DocPaths.PACKAGE_FRAME,
                      packageLabel, "", "packageFrame");
          }
          Content li = HtmlTree.LI(packageLinkContent);
          return li;
      }
docs: Gets each package name as a separate link.
  
  @param pd PackageDoc
  @return content for the package link