Connecting Html file in rocket-rust. How can i connect my html file in through core

fn make_cors() -> Cors {
    let allowed_origins = AllowedOrigins::some_exact(&[
        // allow request from these
                                          // allow from local machine
    CorsOptions {
        allowed_methods: vec![Method::Get, Method::Post, Method::Put, Method::Delete]
        allowed_headers: AllowedHeaders::some(&[
        allow_credentials: true, // without user name and password
    .to_cors() // convert to cross origin
    .expect("Error while building the Cros")