Sync NNAPI Operand and Operation documentation fixes

This CL adds the typo fixes, bug fixes, and missing descriptions added
to the NNAPI but not to the NN HAL. This CL also adds description of
implicit padding, which was present but not documented in 1.0.

Bug: 77541934
Bug: 75459529
Test: mma
Change-Id: I7baa9e515057c43e759849284b3bb0d420a71f1b