Merge pull request w3c#8038 from romainmenke/patch-3

[css-nesting] fix `@layer` example

Author: Adam Argyle

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%;
 					}