Support for common markdown callouts like NOTE, TIP, HINT

[KingOfSpades]

Checklist

• I have read the contributing guidelines.
• There is no similar request on existing issues (including closed ones).
• I have read the project progress and know the current progress of the project.
• I was in the master branch of the latest code.

Is your feature request related to a problem? Please describe

No

Describe the solution you'd like

Support for callouts (sometimes called alerts or admonitions) that set off their contents visually. For example, NOTE, WARN or INFO could wrap the content that follows in a yellow, red or blue container, and/or change the font color.

This has been implemented on the theme "just-the-docs" in the following style: https://pdmosses.github.io/just-the-docs-tests/docs/css/admonitions.html

Describe alternatives you've considered

The alternative I'am currently using is in the form of the following code:
For a warning:

<div markdown="span" class="alert alert-danger" role="alert"><i class="fa fa-exclamation-circle"></i> <b>Warning:</b> Mounting a volume on path that already exists on a pod will make all files in that directory inaccessible</b>
</div>

Renders to:

• Light mode:
  

• Dark mode:
  

Additional context

[KingOfSpades]

Awesome!