[css-cascade-6][editorial] Add example of implicit scope root

Author: mirisuzanne

css-cascade-6/Overview.bs

@@ -513,6 +513,38 @@ Identifying Scoping Roots and Limits</h4>
 		interpreting '':scope'' and ''&''
 		exactly as in [=scoped style rules=].
 
+	<div class=example>
+		Authors can establish local scoping
+		for <{style}> elements by leaving out the <<scope-start>> selector.
+		For example:
+
+		<pre class=lang-html>
+		&lt;div>
+		  &lt;style>
+		    @scope {
+		      p { color: red; }
+		    }
+		  &lt;/style>
+		  &lt;p>this is red&lt;/p>
+		&lt;/div>
+		&lt;p>not red&lt;/p>
+		</pre>
+
+		That would be equivalent to:
+
+		<pre class=lang-html>
+		&lt;div id="foo">
+		  &lt;style>
+		    @scope (#foo) {
+		      p { color: red; }
+		    }
+		  &lt;/style>
+		  &lt;p>this is red&lt;/p>
+		&lt;/div>
+		&lt;p>not red&lt;/p>
+		</pre>
+	</div>
+
 	<div class=example>
 		[=Scoping limits=] can use the '':scope'' pseudo-class
 		to require a specific relationship to the [=scoping root=]: