Merge "Improve the docs about when to use introduced." into main am: 04e52144 am: 4a229716

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/2812358



Change-Id: I3299961435fdadd051968b9a83d60272009e3ce5
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>