init.php

<?php
/**
 * Init hooks.
 *
 * @package gutenberg
 */

/**
 * Gutenberg's Menu.
 *
 * Adds a new wp-admin menu page for the Gutenberg editor.
 *
 * @since 0.1.0
 */
function gutenberg_menu() {
	add_menu_page(
		__( 'Gutenberg', 'gutenberg' ),
		__( 'Gutenberg', 'gutenberg' ),
		'edit_posts',
		'gutenberg',
		'',
		'dashicons-edit'
	);

	add_submenu_page(
		'gutenberg',
		__( 'Demo', 'gutenberg' ),
		__( 'Demo', 'gutenberg' ),
		'edit_posts',
		'gutenberg'
	);

	if ( current_user_can( 'edit_posts' ) ) {
		add_submenu_page(
			'gutenberg',
			__( 'Support', 'gutenberg' ),
			__( 'Support', 'gutenberg' ),
			'edit_posts',
			__( 'https://wordpress.org/support/plugin/gutenberg/', 'gutenberg' )
		);
		add_submenu_page(
			'gutenberg',
			__( 'Documentation', 'gutenberg' ),
			__( 'Documentation', 'gutenberg' ),
			'edit_posts',
			'https://developer.wordpress.org/block-editor/'
		);
	}

	add_submenu_page(
		'gutenberg',
		__( 'Experiments Settings', 'gutenberg' ),
		__( 'Experiments', 'gutenberg' ),
		'manage_options',
		'gutenberg-experiments',
		'the_gutenberg_experiments'
	);
}
add_action( 'admin_menu', 'gutenberg_menu', 9 );