docs: How to get specific fields when listing files.

Hey,

How is it going with this project? I am planning to use this for my own project and was trying some things. However I could not find how to get certain fields of a file, like id, name, parents. etc..
The documentation also isn't clear this one.
I am willing to help with the project, to get it more usable. Love to hear from you.

Regards,