Mention customization of next.config.js to import images (#27104)

Fixes #27094



## Bug

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

## Documentation / Examples

- [ ] Make sure the linting passes

docs/upgrading.md

@@ -56,6 +56,18 @@ Example:
 PORT=4000 next start
 ```
 
+### `next.config.js` customization to import images
+
+Next.js 11 supports static image imports with `next/image`. This new feature relies on being able to process image imports. If you previously added the `next-images` or `next-optimized-images` packages you can either move to the new built-in support using `next/image` or disable the feature:
+
+```js
+module.exports = {
+  images: {
+    disableStaticImages: true,
+  },
+}
+```
+
 ### Remove `super.componentDidCatch()` from `pages/_app.js`
 
 The `next/app` component's `componentDidCatch` has been deprecated since Next.js 9 as it's no longer needed and has since been a no-op, in Next.js 11 it has been removed.