How do we insert our own datasets in DPR / RAG retrieval Q&A models?

See example here for RAG:

This example uses a dummy dataset. It is not immediately clear to me how I would convert to use my own dataset of choice. Anyone know how that can be done?

There is no tutorial on how to do it, although it should be possible.

There is an issue discussing this:
https://github.com/huggingface/transformers/issues/7462