xenvm: doc: Update docs for Xen VM according to new evtchn functionality
xenvm: doc: Update docs for Xen VM according to new evtchn functionality

Signed-off-by: Dmytro Firsov <9800c905ad516cb69a0a44d48b2e9aea877d3a61@epam.com>

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