docs: add missing article

Signed-off-by: Jens Oliver Meiert <jens@meiert.com>

Author: j9t

css-text-4/Overview.bs

@@ -5652,7 +5652,7 @@ Joint Wrapping Control: the 'text-wrap' shorthand property</h3>
 		parsing/white-space-shorthand-text-wrap.html
 	</wpt>
 
-	This property is a shorthand for 'text-wrap-mode' and 'text-wrap-style' properties.
+	This property is a shorthand for the 'text-wrap-mode' and 'text-wrap-style' properties.
 	Any omitted [=longhand=] is set to its [=initial value=].
 
 <h3 id="line-break-details">