docs: show possible similar pages on 404 page (#13840)

* docs: show possible similar pages on 404 page

* fix 404 page in api reference

www/apps/api-reference/app/not-found.tsx

@@ -0,0 +1,58 @@
+import { AcademicCapSolid, BookOpen } from "@medusajs/icons"
+import clsx from "clsx"
+import { CardList, H1, H2, MDXComponents, SimilarPages } from "docs-ui"
+import { config } from "../config"
+
+const P = MDXComponents.p as React.FC<
+  React.HTMLAttributes<HTMLParagraphElement>
+>
+const A = MDXComponents.a as React.FC<
+  React.AnchorHTMLAttributes<HTMLAnchorElement>
+>
+
+const NotFoundPage = () => {
+  return (
+    <div
+      className={clsx(
+        "w-full h-fit",
+        "max-w-inner-content-xs sm:max-w-inner-content-sm md:max-w-inner-content-md",
+        "lg:max-w-inner-content-lg xl:max-w-inner-content-xl xxl:max-w-inner-content-xxl",
+        "xxxl:max-w-inner-content-xxxl",
+        "px-docs_1 md:px-docs_4"
+      )}
+    >
+      <H1>Page Not Found</H1>
+      <P>The page you were looking for isn&apos;t available.</P>
+      <P>
+        If you&apos;re looking for Medusa v1 documentation, it&apos;s been moved
+        to <A href="https://docs.medusajs.com/v1">docs.medusajs.com/v1</A>.
+      </P>
+      <P>
+        If you think this is a mistake, please{" "}
+        <A href="https://github.com/medusajs/medusa/issues/new?assignees=&labels=type%3A+docs&template=docs.yml">
+          report this issue on GitHub
+        </A>
+        .
+      </P>
+      <SimilarPages />
+      <H2>Other Resources</H2>
+      <CardList
+        itemsPerRow={2}
+        items={[
+          {
+            title: "Get Started Docs",
+            href: `${config.baseUrl}/learn`,
+            icon: BookOpen,
+          },
+          {
+            title: "Commerce Modules",
+            href: `${config.baseUrl}/resources/commerce-modules`,
+            icon: AcademicCapSolid,
+          },
+        ]}
+      />
+    </div>
+  )
+}
+
+export default NotFoundPage