update navigation menu link component docs next/link usage

[yoonthegoon]

legacyBehavior prop in next/link will be deprecated in v16 vercel/next.js#77473

using the current doc's suggested

<NavigationMenuItem>
  <Link href="/docs" legacyBehavior passHref>
    <NavigationMenuLink className={navigationMenuTriggerStyle()}>
      Documentation
    </NavigationMenuLink>
  </Link>
</NavigationMenuItem>

results in

docs should probably suggest

<NavigationMenuItem>
  <NavigationMenuLink
    className={navigationMenuTriggerStyle()}
    asChild
  >
    <Link href="/docs">Documentation</Link>
  </NavigationMenuLink>
</NavigationMenuItem>