Merge "Document newly updated NDK/Media constants" into udc-dev am: 2bdb535e am: 8b370c9c

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/av/+/22080102



Change-Id: I5465b2f2876495d7b57d86e18b9eb880114948ed
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>