code: protected Content getNavLinkModule(ModuleElement mdle) {
          Content linkContent = getModuleLink(mdle, contents.moduleLabel);
          Content li = HtmlTree.LI(linkContent);
          return li;
      }
docs: Get link to the module summary page for the module passed.
  
  @param mdle Module to which link will be generated
  @return a content tree for the link