Revert "Use h5 for callouts so that they are not included in ToC."

This reverts commit 11da160114.

This is no longer needed with jekyll-toc 0.9.1.

site/docs/4.1/utilities/colors.md

@@ -49,7 +49,7 @@ When `$enable-gradients` is set to `true` (default is `false`), you can use `.bg
 - `.bg-gradient-{{ color.name }}`{% endfor %}
 
 {% capture callout %}
-##### Dealing with specificity
+#### Dealing with specificity
 
 Sometimes contextual classes cannot be applied due to the specificity of another selector. In some cases, a sufficient workaround is to wrap your element's content in a `<div>` with the class.
 {% endcapture %}