code: protected void addPackageUse(PackageDoc pkg, Content contentTree) throws IOException {
          Content tdFirst = HtmlTree.TD(HtmlStyle.colFirst,
                  getHyperLink(pkg.name(), new StringContent(Util.getPackageName(pkg))));
          contentTree.addContent(tdFirst);
          HtmlTree tdLast = new HtmlTree(HtmlTag.TD);
          tdLast.addStyle(HtmlStyle.colLast);
          addSummaryComment(pkg, tdLast);
          contentTree.addContent(tdLast);
      }
docs: Add the package use information.
  
  @param pkg the package that uses the given class
  @param contentTree the content tree to which the package use information will be added