Fix typo for ReactDOM method inside generate-metadata.mdx

Fixed a typo that incorrectly stated the existence of ReactDOM.preconnectDNS when it should be declared as ReactDOM.prefetchDNS instead.

docs/02-app/02-api-reference/04-functions/generate-metadata.mdx

@@ -1041,7 +1041,7 @@ ReactDOM.prefetchDNS(href: string)
 >
 > - These methods are currently only supported in Client Components, which are still Server Side Rendered on initial page load.
 > - Next.js in-built features such as `next/font`, `next/image` and `next/script` automatically handle relevant resource hints.
-> - React 18.3 does not yet include type definitions for `ReactDOM.preload`, `ReactDOM.preconnect`, and `ReactDOM.preconnectDNS`. You can use `// @ts-ignore` as a temporary solution to avoid type errors.
+> - React 18.3 does not yet include type definitions for `ReactDOM.preload`, `ReactDOM.preconnect`, and `ReactDOM.prefetchDNS`. You can use `// @ts-ignore` as a temporary solution to avoid type errors.
 
 ## Types