[css-flexbox] Remove accidental <dfn>s in the Changes section.

Author: tabatkins

css-flexbox/Overview.bs

@@ -3457,7 +3457,7 @@ Clarifications</h4>
 				<ins>
 					<p>A <a>flex item</a> is <a>fully inflexible</a>
 					if both its 'flex-grow' and 'flex-shrink' values are zero,
-					and <dfn>flexible</dfn> otherwise.</p>
+					and <a>flexible</a> otherwise.</p>
 				</ins>
 			</blockquote>
 			<blockquote>
@@ -3474,7 +3474,7 @@ Clarifications</h4>
 					On a <a>flex item</a> whose 'overflow' is ''overflow/visible'' in the <a>main axis</a>,
 					when specified on the <a>flex item's</a> main-axis min-size property,
 					<del>the following table gives the minimum size &hellip;</del>
-					<ins>specifies an <dfn dfn export>automatic minimum size</dfn>.</ins>
+					<ins>specifies an <a>automatic minimum size</a>.</ins>
 				</p>
 				<ins><p>
 					In general, the <a>automatic minimum size</a> &hellip; defined below: