register url

// Add Login/Logout to Main Menu
    function add_loginout_link( $items, $args ) {
        if (is_user_logged_in() && $args->theme_location == 'primary') {
            $items .= '<li><a href="'. wp_logout_url() .'">Log Out</a></li>';
        }
        elseif (!is_user_logged_in() && $args->theme_location == 'primary') {
            $items .= '<li><a href="'. wp_registration_url() .'">Join</a></li><li><a href="'. site_url('wp-login.php') .'">Log In</a></li>';
        }
        return $items;
    }
    add_filter( 'wp_nav_menu_items', 'add_loginout_link', 10, 2 );

    // Add Login/Logout to Hamburger Menu
    function add_hamburger_loginout_link( $items, $args ) {
        if (is_user_logged_in() && $args->theme_location == 'hamburger') {
            $items .= '<li><a href="'. wp_logout_url() .'">Log Out</a></li>';
        }
        elseif (!is_user_logged_in() && $args->theme_location == 'hamburger') {
            $items .= '<li><a href="'. wp_registration_url() .'">Join</a></li><li><a href="'. site_url('wp-login.php') .'">Log In</a></li>';
        }
        return $items;
    }
    add_filter( 'wp_nav_menu_items', 'add_hamburger_loginout_link', 10, 2 );

    // Change Register URL
    add_filter( 'register_url', 'my_register_page' );
    function my_register_page( $register_url ) {
        return home_url( '/join/' );
    }