Entryway, add not_implemented endpoint to router

entryway/src/main.rs

@@ -31,6 +31,7 @@ async fn main() {
 
   let mut router = Router::new();
   let create_account_nsid: Nsid = "com.atproto.server.createAccount".parse::<Nsid>().expect("valid nsid");
+  router = router.add_endpoint(XrpcEndpoint::not_implemented());
   router = router.add_endpoint(XrpcEndpoint::new_procedure(create_account_nsid, create_account));
   router.serve().await;
 }