Tooltips

[JakeSCahill]

We have lots of helpful links, but sometimes we don't want to make readers go to a different page to find out what something is.

We also don't want to clog the page full of definitions.

It'd be great to have tooltip markdown so that we can have a short explanation appear on hover.

[obany]

Good idea, although worth remembering there is no hover on mobile, so you may need a small info icon that you can press.