[css-values-4] fix typo

Author: fantasai

css-values-4/Overview.bs

@@ -4956,7 +4956,7 @@ Recent Changes</h3>
 		<li>Updated to match latest Fetch terminology.
 			(<a href="https://github.com/whatwg/fetch/pull/1413">Fetch PR 1413</a>,
 			 <a href="https://github.com/w3c/csswg-drafts/pull/7160">CSS PR 7160</a>)
-		<li>	Clarified that the [=font-relative lenghts=] are calculated without text shaping.
+		<li>	Clarified that the [=font-relative lengths=] are calculated without text shaping.
 	</ul>
 
 	Substantial changes since <a href="https://www.w3.org/TR/2021/WD-css-values-4-20211016/">16 October 2021 WD</a>: