Update to Lit 2.0.0 (manually)

Will attempt to get this back to syncing with monorepo history per https://github.com/lit/lit#exporting-starter-templates in a follow-up.

docs-src/_includes/footer.11ty.cjs

@@ -3,7 +3,7 @@ module.exports = function (data) {
 <footer>
   <p>
     Made with
-    <a href="https://github.com/PolymerLabs/lit-starter-ts">lit-starter-ts</a>
+    <a href="https://github.com/lit/lit-element-starter-ts">lit-starter-ts</a>
   </p>
 </footer>`;
 };