Adds ability to show modifier markup and example

By escaping the modifier markup in the template, it’s possible to show both the example, and a more contextual code sample. That way, the templates can show this:

```css
<div class="button button--large">Submit</div>
```

Instead of this:

```css
<div class="button {$modifiers}">Submit</div>
```

I find this helpful for removing some confusion around `{$modifiers}`, and for providing the specific markup for each modifier. Let me know what you think!