Fix gatsby ssr

Author: pomber

examples/gatsby/gatsby-ssr.js

@@ -0,0 +1,7 @@
+import "@code-hike/mdx/styles.css"
+import React from "react"
+import { Layout } from "./src/components/layout"
+
+export const wrapPageElement = ({ element, props }) => {
+  return <Layout {...props}>{element}</Layout>
+}