Docs: Grammar fix (it's -> its) am: 444b464c am: b8d216e4

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/23829884



Change-Id: I3ba4520b8a4e7c848bb64616d5d1fd7f3b0d72d4
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>