Add defaults for <details> and <summary> in typography plugin

[tobihagemann]

Would it make sense to add default stylings for <details> and <summary> in the typography plugin?

Reference: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/details

I think that it's quite useful in Markdown, it even works in GitHub:

Details

Something small enough to escape casual notice.

Any thoughts on that?