Update Overview.bs

Author: romainmenke

css-nesting-1/Overview.bs

@@ -450,7 +450,7 @@ Syntax {#syntax}
 		  html {
 				block-size: 100%;
 
-				@layer base.support {
+				@layer support {
 					& body {
 						min-block-size: 100%;
 					}
@@ -1013,4 +1013,4 @@ via [=serialize a CSS rule=].
 	and expecting
 
 	(<a href="https://github.com/w3c/csswg-drafts/issues/7850">Issue 7850</a>)
-</div>
+</div>