[css-exclusions-1] Don't export common terms defined elsewhere like content area.

Author: fantasai

css-exclusions-1/Overview.bs

@@ -61,7 +61,7 @@ Value Definitions</h3>
 <h2 id="terms">
 Terminology</h2>
 
-  <dl export>
+  <dl>
     <dt><dfn>Exclusion box</dfn>
     <dd>
       A <a href="https://www.w3.org/TR/css3-box/">box</a> ([[!CSS3BOX]]) that defines
@@ -891,4 +891,4 @@ Acknowledgments</h2>
     <li>Improved exclusion order example.
     <li>Editorial and markup fixes.
     <li>See also the Changes section of <a href="https://www.w3.org/TR/css-shapes/#20120503">CSS Shapes</a>.
-  </ul>
+  </ul>