Merge "Update docs to highlight the ad-hoc process for riscv64." into main am: 51a4dc5731

Original change: https://android-review.googlesource.com/c/platform/prebuilts/runtime/+/3216188

Change-Id: I667712b9ce11e5cb725d917c90b60b839dc9d9dc
Signed-off-by: Automerger Merge Worker <[email protected]>