Yeah, it would be really easy to do. Here's an example of how you could do the HTML:
You would of course have to define "infobox-info" in your CSS so it displays an indented box with an info icon. You would probably also want to define "infobox-important" and whatever other types of box you might want.
Code:
<aside class="infobox-info">
Note: Localhost is derpy...
</aside>
You would of course have to define "infobox-info" in your CSS so it displays an indented box with an info icon. You would probably also want to define "infobox-important" and whatever other types of box you might want.