Allow markdown in field hints

Would it be possible for the `hint` parameter to be able to render markdown text?

As an editor, the text below each field is a very valuable place for including helpful reminders, style examples, links to the style guide, etc... Having the ability to make certain words bold, italic, add links is super helpful, if not essential.

**Here is an example of the summary field:**
```
- label: "Summary"
name: "summary"
minimal: true
widget: "string"
default: ""
hint: "One-sentence description of the event. _(e.g. Artist [Name] with writer [Name], discuss creative life in the context of our new social reality.)_"
```