doc(Server): Fix doc example
@@ -334,7 +334,7 @@ static CLIENTS: Lazy<Clients> = Lazy::new(Clients::new);
/// use stencila::rpc::Protocol;
/// use stencila::serve::serve_on;
///
-/// serve_on(Protocol::Ws, "127.0.0.1", 9000, None);
+/// serve_on(Protocol::Ws, "127.0.0.1".to_string(), 9000, None);
/// ```
#[tracing::instrument]
pub async fn serve_on(
