Fix warning messages for next export (#41165)

## Bug
Noticed the warning messages don't have spaces. Just adding spaces for better messaging. 
<img width="1714" alt="image" src="https://user-images.githubusercontent.com/1635852/193907658-f3c7d90b-1b91-44bf-b93b-915ab4a635f1.png">

- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have a helpful link attached, see `contributing.md`

## Feature

- [ ] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have a helpful link attached, see `contributing.md`

## Documentation / Examples

- [ ] Make sure the linting passes by running `pnpm lint`
- [ ] The "examples guidelines" are followed from [our contributing doc](https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md)

packages/next/server/render.tsx

@@ -465,8 +465,8 @@ export async function renderToHTML(
   ) {
     warn(
       `Detected getInitialProps on page '${pathname}'` +
-        `while running "next export". It's recommended to use getStaticProps` +
-        `which has a more correct behavior for static exporting.` +
+        ` while running "next export". It's recommended to use getStaticProps` +
+        ` which has a more correct behavior for static exporting.` +
         `\nRead more: https://nextjs.org/docs/messages/get-initial-props-export`
     )
   }