Support hyperlinks in text

[david-a-wheeler]

It's important to be able to easily cite more information in the criteria, e.g., in the text of the criterion's requirements, its objective (rationale), and implementation (details). People expect to be able to click on a hypertext link to get more information. We should support that.

[funnelfiasco]

This is already supported by using Markdown links in the yaml text. For example

...data [or else](https://www.youtube.com/watch?v=7I-mdoClMVA)

See the (commit) and https://funnelfiasco.github.io/security-baseline/#osps-01 for a rendered example (at least until I need to deploy something else to test it)