Add a 410 error page replicating the Sela 404 page

<?php

/**

 * The template for displaying 410 pages (Gone).

 *

 * @package Sela Child

 */

get_header(); ?>

	<div id="primary" class="content-area">

		<main id="main" class="site-main" role="main">

			<section class="error-410">

				<header class="page-header">

					<h1 class="page-title"><?php _e( 'Oops! That page has been removed', 'sela-child' ); ?></h1>

				</header><!-- .page-header -->

				<div class="page-content">

					<p><?php _e( 'This page previously existed but has been deleted; there is nothing to replace it.', 'sela-child' ); ?></p>

					<?php get_search_form(); ?>

				</div><!-- .page-content -->

			</section><!-- .error-410 -->

		</main><!-- #main -->

	</div><!-- #primary -->

<?php get_footer(); ?>