Looking through CoreLibs in the SDK, I noticed that there were a couple files that didn't have any mention in the reference. Documenting utility functions like playdate.getPitchAndRoll might save devs from having to write the code over again.
I understand it wouldn't be very high on the list, but it might be helpful to document these missing libraries:
CoreLibs/3dCoreLibs/accelerometerCoreLibs/logicCoreLibs/save