In order to add related articles to the bottom of an article, all you have to do is add articles to the related field at the top of the .md file for the article in question.
The related field is an array of strings, for example ["section_name/article1.md", "section_name/article2.md"]. Links are listed in order, so the first link in the related field is the first link printed on the resulting page.
For example, this is the "front-matter" for this article:
+++
title = "List Related Articles"
description = "How to list related articles at the bottom of an article"
[extra]
related = ["meta/create_article.md", "meta/edit_front_page_featured_articles.md"]
+++