Add better instructions in Preview

Author: exacs

samples/graph-webhooks-cache-invalidation/src/app/preview/page.tsx

@@ -3,11 +3,10 @@ import React from 'react';
 export default function Page() {
   return (
     <div>
-      This sample site doesn&apos;t have Live Preview enabled. Go to{' '}
-      <a href="/en/" target="_blank">
-        /en
-      </a>{' '}
-      to see the actual page instead
+      This sample site doesn&apos;t support hooks revalidation in Preview mode.
+      Go to the page in view mode by clicking{' '}
+      <strong>Options &larr; View in page</strong>
+      to test hooks revalidation
     </div>
   );
 }