Ability to highlight parts of the code

[davidtlee]

Hi, I was wondering whether ngx-markdown supports markdown for highlighting parts within a codeblock. For example, like in the learn svelte tutorial:

This is the markdown: https://github.com/sveltejs/learn.svelte.dev/blob/main/content/tutorial/01-svelte/01-introduction/02-your-first-component/README.md
This is how it is rendered: https://learn.svelte.dev/tutorial/your-first-component

In this example, they use surrounding +++ characters to denote something as being highlighted (here is one bit of that copy-pasted below):

/// file: App.svelte
<h1>Hello +++{name}+++!</h1>

[RoyceTheBiker]

I would also find this a helpful feature.