Add to API FAQ or Introduction use of PersistentID vs. Dataset or FileID in API Commands

Someone please edit the title of this issue.

Overview of the Feature Request
Add more information on how API commands are composed. Help to make the examples more understandable and that in some cases an API command (example) uses a dataset and/or file ID and other times the persistentID is used. The syntax of the API is slightly different for these different uses.

What kind of user is the feature intended for?
Improved documentation for API users

What inspired the request?
Google Groups question (end of this thread: https://groups.google.com/g/dataverse-community/c/TqXmICwr0io?hl=en)
and this NOTE from the guides: https://guides.dataverse.org/en/latest/api/dataaccess.html#basic-file-access

What existing behavior do you want changed?
Let API users understand there is more than one way to write API commands especially when the documents may use either of the ways.

Start with the API FAQ or Introduction and the linked guides section on basic file access. Compare the existing API command examples that use dataset or FileID with those using persistentID, then clarify the syntax differences and make the examples understandable for API users. Done means the documentation explains when each identifier form is used.