Convert documentation to Gitlab pages with markdown

Problem/Motivation

As discussed during the meeting 📌 [Monthly Meeting] UI Suite Initiative 2024-11-14 Active , let's convert documentation into Gitlab pages with markdown.

https://project.pages.drupalcode.org/gitlab_templates/jobs/pages/

- UI Patterns: https://www.drupal.org/docs/extending-drupal/contributed-modules/contrib... →
- UI Styles: https://www.drupal.org/docs/extending-drupal/contributed-modules/contrib... →
- UI Suite Bootstrap: https://git.drupalcode.org/project/ui_suite_bootstrap/-/tree/5.1.x/docs?...

Some READMEs and project page could be lighten to extract code examples into proper documentation too?