chore: restore secondary copyright banners

These files dropped the '/* Copyright (c) Facebook, Inc. */' banner when
the 'use client' directive was added. Restore it above the directive
(comments may precede a directive without disabling it).

Author: aurorascharff

src/components/Layout/Page.tsx

@@ -5,6 +5,10 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ */
+
 'use client';
 
 import {Suspense} from 'react';

src/components/MDX/MDXComponents.tsx

@@ -5,6 +5,10 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ */
+
 'use client';
 
 import {Children, useContext, useMemo} from 'react';

src/components/Search.tsx

@@ -5,6 +5,10 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ */
+
 'use client';
 
 import Link from 'next/link';

src/hooks/usePendingRoute.ts

@@ -5,6 +5,10 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ */
+
 // App Router has no equivalent of router.events. Pending-state highlighting is
 // dropped; <Link> still triggers transitions internally.
 const usePendingRoute = (): string | null => null;