Add better image support for markdown content

[lyzadanger]

Currently adding images manually in blog posts and content, e.g.

![Best Meats Sold Anywhere](https://res.cloudinary.com/dfsssdwbu/image/upload/c_fit,w_1200/v1707427658/best-meats_wztdic.jpg)

Note the use of Cloudinary transform API in the URL here. And there's no ability to caption images, nor...various things.

What I'd like is:

• Ability to caption images (possibly use <figure> element or similar)
• Ability to auto-craft CDN URLs for images

Given that I don't want to pollute my markdown source/couple it to 11ty, I might come at this by writing markdown-it plugins. e.g. might crib from https://github.com/windmaomao/markdown-it-figure-caption for captioning.

[lyzadanger]

See also: https://github.com/markdown-it/markdown-it/blob/master/docs/architecture.md

[lyzadanger]

Also handy reference: https://github.com/solution-loisir/markdown-it-eleventy-img/blob/master/index.js

(That project is a markdown-it plugin that uses Eleventy's eleventy-img plugin additionally, to resize/transform the images themselves. I believe I'd like to stay away from doing the image transforms and instead just transform the markdown-to-html output. I am probably more keen on adding figure elements and captions than using a picture element. So sue me.)