Add images to boilerplate project

Hi,

I want to start creating a custom lovelace card.
I am using https://github.com/custom-cards/boilerplate-card

How do I add images, so that they would be in the plugin, and not needed to add to ha itself?
Or am I missing something really simple here, like I cannot do this, and need to add the files manually?

(I really like that project)

Thanks