I think the italicized description if the best option right now, but please feel free to send a feature request for this: https://github.com/dendronhq/dendron/issues/new/choose You can also try adding HTML into the note for this, although gitlab might block that:

<figure>
<img src="https://example.com/image.png">
<figcaption style="font-style: italic">This is the caption.</figcaption>
</figure>