Change docs to include aaudio/Aaudio.h

Currently, the docs incorrectly include AAudio.h
See https://developer.android.com/ndk/reference/group/audio

This needs to be changed to aaudio/AAudio.h

Bug: 120860319
Test: not sure how to verify docs
Change-Id: I3365721a42b6f44613ca21a4e9e76af64777f0e4