Merge "Extend target docs to cover (almost) all variants." am: 2c7ca784 am:...

Merge "Extend target docs to cover (almost) all variants." am: 2c7ca784 am: fde70e4d am: 8a5f9ff3

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/1435494

Change-Id: I3259a199bcef4f047c423736ee2e52e9451b02fc