feat(php): add the change in the migration guide

Author: damcou

website/docs/clients/migration-guides/php.md

@@ -6,6 +6,8 @@ title: PHP
 | -------------------- | :------------------------------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
 | `"algolia/algoliasearch-client-php": "^3.2"`           | `"algolia/algoliasearch-client-php": "^4.0@alpha"`  | **During the beta phase**, the clients are available under the package 4.x.x-alpha , you can find a full list [here](https://packagist.org/packages/algolia/algoliasearch-client-php).      |
 | `Algolia\AlgoliaSearch`             | `Algolia\AlgoliaSearch\Api`                         | Exported clients have now the namespace suffixed by `Api`.                                                                                                                                                                                |
+| `Algolia\AlgoliaSearch\Cache\FileCacheDriver`             | **removed**                      |  This implementation of the `CacheInterface` is not available anymore in the Client. If you feel the need for it, [please open an issue](https://github.com/algolia/api-clients-automation/issues/new?assignees=&labels=&template=Feature_request.md)                                                                                                                                                                              |
+
 
 ### Usage