Merge "Extend the docs somewhat to avoid downloading unneeded prebuilts when doing an update." into main am: a27964c3ee am: 0eb1a78645

Original change: https://android-review.googlesource.com/c/platform/prebuilts/runtime/+/2785966

Change-Id: I05715b70f9a60232cd839d1ec2061d0df4e24944
Signed-off-by: Automerger Merge Worker <[email protected]>