Docs: move redirects to global config, remove client-side redirect page

Co-Authored-By: Craft Agent <agents-noreply@craft.do>

docs/app/usage/introduction/page.tsx

@@ -1,12 +0,0 @@
-"use client";
-
-import { useEffect } from "react";
-import { useRouter } from "next/navigation";
-
-export default function Page() {
-   const router = useRouter();
-   useEffect(() => {
-      router.replace("/usage/setup/");
-   }, [router]);
-   return null;
-}