[css-flexbox-1][editorial] Fix link to “definite” w3c#10543

Author: fantasai

css-flexbox-1/Overview.bs

@@ -3730,8 +3730,8 @@ Changes since the <a href="https://www.w3.org/TR/2018/CR-css-flexbox-1-20181119/
 			</blockquote>
 			<blockquote>
 				<p class="note"><del>Note: The main size of a <a>fully inflexible</a> item
-				with a <a>definite</a> <a>flex basis</a>
-				is, by definition, <a>definite</a>.</del>
+				with a <a spec=css-sizing-3>definite</a> <a>flex basis</a>
+				is, by definition, <a spec=css-sizing-3>definite</a>.</del>
 
 				<p class="note"><ins>Note: This means that within [=flex layout=],
 				“definite” sizes can require performing layout.