doc: update release tagging procedures
doc: update release tagging procedures

Clean up and update release tagging procedures. Use new
document tabs to separate instructions for release
candidate and final releases.

Signed-off-by: David Leach <98707a1e43c521c5b5b81e36afef696dde6831a3@nxp.com>

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