Bluetooth: Mesh: Add information about secure provisioning
Bluetooth: Mesh: Add information about secure provisioning

This clarification helps implementers to choose provisioning process
parameters.

Signed-off-by: Omkar Kulkarni <78d7b7656bddf3262590a73d9e4547e08c9a5842@nordicsemi.no>

finikorg/zephyr,finikorg/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,finikorg/zephyr,galak/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr