Previously the large and small callouts were headed with 'This is a secondary panel' even though it wasn't actually a secondary callout and as a visual description doesn't match the styles used in the coloring section.
This PR modifies the header text in these examples to match the style used in the coloring section and explains the example using the class names ('small callout' and 'large callout') in the same manner as with the coloring section.
```html_example
<div class="callout small">
- <h5>This is a secondary panel</h5>
+ <h5>This is a small callout</h5>
<p>It has an easy to override visual style, and is appropriately subdued.</p>
<a href="#">It's dangerous to go alone, take this.</a>
</div>
<div class="callout large">
- <h5>This is a secondary panel</h5>
+ <h5>This is a large callout</h5>
<p>It has an easy to override visual style, and is appropriately subdued.</p>
<a href="#">It's dangerous to go alone, take this.</a>
</div>