RAG(Retrieval-Augmented Generation) to avoid hallucination

https://yoandev.co/construire-un-rag-en-php-avec-la-doc-de-symfony-llphant-et-openai

I would like to have the ability to find and serve material only from uploaded files to avoid hallucination. I would like to have an assistant that can search multiple files, such as PDf, DOC, etc.