[selectors-4] Add textarea to placeholder example #6669

Author: fantasai

selectors-4/Overview.bs

@@ -2659,7 +2659,7 @@ The Placeholder-shown Pseudo-class: '':placeholder-shown''</h4>
 
 	<div class="example">
 		For example, according to the semantics of [[HTML]]
-		the <{input/placeholder}> attribute on the <{input}> element
+		the <{input/placeholder}> attribute on the <{input}> and <{textarea}> elements
 		provide placeholder text,
 		as does the first <{option}> element of a <{select}> under certain conditions.
 		The '':placeholder-shown'' class thus applies