http_response_headers.module

<?php

/**
 * @file
 * HTTP Header manipulations module.
 */

use Drupal\Core\Url;
use Drupal\Core\Link;
use Drupal\Core\Routing\RouteMatchInterface;

/**
 * Implements hook_help().
 */
function http_response_headers_help($route_name, RouteMatchInterface $route_match) {
  if ($route_name !== 'help.page.http_response_headers') {
    return '';
  }

  $output = '<h3>HTTP Repsonse Headers Help</h3>';

  $output .= 'This module provides basic security headers by default. But in most cases will require further configuration based on your requirements.';

  $help = [
    '#theme' => 'item_list',
    '#list_type' => 'ul',
    '#title' => 'For more information about security headers visit:',
    '#items' => [
      Link::fromTextAndUrl('securityheaders.io', Url::fromUri('https://securityheaders.io/')),
      Link::fromTextAndUrl('scotthelme.co.uk', Url::fromUri('https://scotthelme.co.uk/')),
    ],
    '#attributes' => ['class' => 'help-resources'],
    '#wrapper_attributes' => ['class' => 'container'],
  ];
  $output .= render($help);

  return $output;
}