Change the number of categories and the order on the homepage when using Storefront

functions.php

add_filter('storefront_product_categories_shortcode_args','custom_storefront_category_per_page' );

// Category Products
function custom_storefront_category_per_page( $args ) {
	$args['number'] = 10;
	$args['orderby'] = 'name';
	return $args;
}