Add support for image captions

[muodov]

How about adding captions so images? For my needs, I am using this approach, but it would be nice to have it out of the box in Pixyll.

[plttn]

FWIW, I'm not 100% sure that a theme could add this feature.

[mattkosoy]

you could do something like this:

_![this is a big image](https://i.ytimg.com/vi/gLg6qxkQ94A/maxresdefault.jpg)_
<footer><cite title="Whoa.">That's going to leave a mark</cite></footer>

Check out the citation footer in @johnotander's original example.

Hope this helps.