Gets when the page data was last modified.
import wixSiteFrontend from "wix-site-frontend";
// ...
wixSiteFrontend.routerSitemap("routerPrefix").then((routerSitemap) => {
const firstEntryLastModified = routerSitemap[0].lastModified; // 'Fri Oct 13 2022 11:23:56 GMT+0300'
});