Simple Styleguide was created to be a fully flexible styleguide for Drupal site builders. This module creates the styleguide you need and nothing more. No elements are required. No elements are added by default. And all this functionality is fully accessible to site builders without having to write code.

Module page: https://www.drupal.org/project/simple_styleguide

composer require drupal/simple_styleguide

You can choose from a set of very basic default patterns such as headings, text, lists, blockquote, horizontal rules, table, alerts, breadcrumbs, forms, buttons, and pagination. Chosen elements will appear on the styleguide page. Choose as many default options as you like, or choose none.

You can also create custom patterns. Custom patterns can be any chunk of html that you want. There are no restrictions.

You also have the ability to create a color palette by adding a hex color code, a class name, and usage descriptions.

With these tools you can create a very flexible styleguide/pattern library. All of this can be accomplished without ever touching a line of code (other than your site's css).

Settings
http://yoursite.com/admin/config/styleguide/settings

Viewing
http://yoursite.com/simple-styleguide