rtos_sdk: docs: add aocpu (s5,t5m,t3x) access limitation [1/1]

PD#SWPL-132819

Problem:
add aocpu access limitation docs.

Solution:
add aocpu access limitation docs in arch/riscv.

Verify:
make docs

Change-Id: I06ef581e51f1d315872f5fe6940236f8d5848c34
Signed-off-by: bangzheng.liu <bangzheng.liu@amlogic.com>
4 files changed