For my blogpost http://websupporter.net/blog/de/starter-content-fuer-themes/

starter-content-add-menus.php

<?php

add_action( 'after_setup_theme', 'theme_start_content' );
function theme_starter_content() {

	add_theme_support( 'starter-content', array(
		'posts' => array(
			'home',
			'test' => array(
				'post_type'    => 'page',
				'post_title'   => _x( 'Das ist ein Test', 'theme-slug' ),
				'post_content' => _x( 'Hier habe ich eine Testseite angelegt.', 'theme-slug' ),
			),
		),
		'nav_menus' => array(
			'top' => array(
				'name'  => __( 'Top Menu', 'theme-slug' ),
				'items' => array(
					'page_home',
					array(
						'type'      => 'post_type',
						'object'    => 'page',
						'object_id' => '{{test}}',
					),
					array(
						'url'   => 'http://websupporter.net/',
						'title' => x( 'Externer Link', 'theme-slug' ),
					),
				),
			),
		)
	) );
}