minor comment change to content-sectioning

Author: chris-pearce

src/content-sectioning.css

@@ -2,7 +2,7 @@
  * We scope our heading styles to classes instead of the `<hx>` element selector
  * so our styles are not tied to their semantics, i.e., if you want a `<h4>` to
  * look like a `<h2>` you can easily do this. All of the heading elements are
- * reset to have the same styles as the base copy. See:
+ * reset to have the same styles as the body copy. See:
  * https://medium.com/fed-or-dead/handling-headings-in-a-ui-component-library-2587de93c890
  */