[css-nesting-1] adds another valid and invalid example to nested conditionals

Author: Adam Argyle

css-nesting-1/Overview.bs

@@ -458,12 +458,32 @@ Nesting Conditional Rules {#conditionals}
     /* equivalent to
        .foo { display: grid; }
 
-       @media (orientation: portrait) {
+       @media (orientation: landscape) {
          .foo { 
            grid-auto-flow: column; 
          }
        }
      */
+
+    .foo {
+      color: red;
+
+      @media (min-width: 480px) {
+        & > .bar,
+        & > .baz { 
+          color: blue;
+        }
+      }
+    }
+    /* equivalent to
+       .foo { color: red; }
+
+       @media (min-width: 480px) {
+         .foo > :is(.bar, .baz) { 
+           color: blue;
+         }
+       }
+     */
     </pre>
 
     But the following are invalid:
@@ -487,6 +507,16 @@ Nesting Conditional Rules {#conditionals}
     }
     /* Invalid because not all selectors in the list
        contain a nesting selector */
+
+    .foo {
+      color: red;
+      
+      @nest @media (min-width: 480px) {
+        & { color: blue; }
+      }
+    }
+    /* Invalid because @nest expects a selector prelude, 
+       instead a conditional rule was provided */
     </pre>
   </div>