[css-flexbox-1] Fix anchor

Author: fantasai

css-flexbox-1/Overview.bs

@@ -3468,7 +3468,7 @@ Changes since the 16 October 2017 CR</h3>
 			they must be resolved against the inline dimension, as for blocks.
 			(<a href="https://github.com/w3c/csswg-drafts/issues/2085">Issue 2085</a>)
 
-		<li id="change-2017-flex-min-content">
+		<li id="change-2017-flex-min-contribution">
 			Floored <a>flex item</a>’s <a>min-content contribution</a>
 			by their specified size ('width'/'height' as appropriate).
 			(<a href="https://github.com/w3c/csswg-drafts/issues/2353">Issue 2353</a>)