Hello Marcus,
Unfortunately Example Driver documentation is not included in s32 Design Studio.
Anyway these drivers could be downloaded as a separate software package called Quick Start Package for FRDM-KEA boards. The zip archive includes documentation in pdf format:
http://cache.nxp.com/downloads/en/board-support-packages/FRDM-KEA-QSP.zip?fsrch=1&sr=7&pageNum=3
Note:
In new version of S32DS the folder name with KEA drivers has been changed from "S32_SDK_KEA_1_0_0" to "Sample_Drivers_for_KEAxxx_Evaluation_grade" to avoid confusion with production drivers dedicated to S32Kx parts (S32 SDK)
Hope it helps
Stan