We are running our website on nopCommerce 3.7 and wondering how to update the Sitemap.xml content since we're adding topic pages to our website frequently, thanks!
If a topic is included in the sitemap it will be included in the Sitemap.xml. In order to include a topic in the Sitemap you should go to Administration -> Content Management -> Topics(Pages) -> Edit your Topic and check the "Include in sitemap" setting.