markdownlint/doc-build/md033.md

This rule is triggered whenever raw HTML is used in a Markdown document:

<h1>Inline HTML heading</h1>

To fix this, use 'pure' Markdown instead of including raw HTML:

# Markdown heading

To allow specific HTML elements anywhere in Markdown content, set the allowed_elements parameter to a list of HTML element names. To allow a specific set of HTML elements within Markdown tables, set the table_allowed_elements parameter to a list of HTML element names. This can be used to permit the use of <br>-style line breaks only within Markdown tables.

Rationale: Raw HTML is allowed in Markdown, but this rule is included for those who want their documents to only include "pure" Markdown, or for those who are rendering Markdown documents into something other than HTML.