Update Overview.bs

Author: sheilamoussavi

selectors-4/Overview.bs

@@ -3552,7 +3552,7 @@ Grammar</h2>
 	like '':is()'',
 	which are similarly generic.
 	Although it does have some minor implications on specificity,
-	simply wrapping a style rule's selector in '':is()''
+	wrapping a style rule's selector in '':is()''
 	effectively "upgrades" it to become forgiving.
 
 	Syntactically, <<forgiving-selector-list>> is equivalent to <code><<any-value>>?</code>.