doc: release notes: Add 2.2 release notes for USB subsystem
doc: release notes: Add 2.2 release notes for USB subsystem

Added usb related notes for Zephyr 2.2

Signed-off-by: Emil Obalski <a38006c9a9911dcd7c7e26537de6a2fa1043ca9e@nordicsemi.no>

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