docs: add missing AppProps import (vercel#43136)

Author: arturbien

examples/with-styled-components-babel/pages/_app.tsx

@@ -1,3 +1,4 @@
+import type { AppProps } from 'next/app'
 import { createGlobalStyle, ThemeProvider } from 'styled-components'
 
 const GlobalStyle = createGlobalStyle`
@@ -20,7 +21,7 @@ const theme: ThemeInterface = {
   },
 }
 
-export default function App({ Component, pageProps }) {
+export default function App({ Component, pageProps }: AppProps) {
   return (
     <>
       <GlobalStyle />