Is your feature request related to a problem? Please describe.
When writing procedures, it's often useful to set off non-essential pieces of information as notes, tips, hints, etc. This ensures that the reader knows which pieces of content are instructional, versus merely informational.

Describe the solution you'd like
Support for callouts that set off their contents visually. For example, NOTE could wrap the content that follows in a yellow container, or change the font color.

Describe alternatives you've considered
It's possible to approximate callouts by using formatting. For example:

Note: This whole note is in italics.

or

Note: The boldness of this note sets it apart.

But these aren't as visually appealing.