hello.php

<?php
/**
 * Retrieve the list of categories the widget belongs to.
 *
 * Used to determine where to display the widget in the editor.
 *
 * Note that currently Elementor supports only one category.
 * When multiple categories passed, Elementor uses the first one.
 *
 * @since 1.0.0
 *
 * @access public
 *
 * @return array Widget categories.
 */
public function get_categories() {
    return [ 'my-section' ];
}