[selectors-4] Fix typo

Author: yuheiy

selectors-4/Overview.bs

@@ -2055,7 +2055,7 @@ The Input Focus-Ring Pseudo-class: '':focus-ring''</h3>
 	(typically via a "focus ring").
 
 	<div class=example>
-		For example, UAs typically display focus indicators on text elements
+		For example, UAs typically display focus indicators on text fields
 		<em>whenever</em> they're focused,
 		to draw attention to the fact that keyboard input will affect their contents.