doc: release: 3.1: Add notes about Atmel
doc: release: 3.1: Add notes about Atmel

Add 3.1.0 release notes for Atmel.

Signed-off-by: Gerson Fernando Budke <0ad1c92223f8f375c46e39c6141096f3d30896b4@gmail.com>

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