Updates workOS auth link for the Next.js (#71335)

The current [link](https://workos.com/docs/user-management) points to
the Node.js integration documentation when it redirects. This update
corrects the URL, directing it to the appropriate Next.js integration
page of WorkOS.

Co-authored-by: JJ Kasper <jj@jjsweb.site>

docs/02-app/01-building-your-application/09-authentication/index.mdx

@@ -1649,7 +1649,7 @@ Now that you've learned about authentication in Next.js, here are Next.js-compat
 - [Stack Auth](https://docs.stack-auth.com/getting-started/setup)
 - [Supabase](https://supabase.com/docs/guides/getting-started/quickstarts/nextjs)
 - [Stytch](https://stytch.com/docs/guides/quickstarts/nextjs)
-- [WorkOS](https://workos.com/docs/user-management)
+- [WorkOS](https://workos.com/docs/user-management/nextjs)
 
 ### Session Management Libraries