doc: release: 3.2: Add POSIX changes
doc: release: 3.2: Add POSIX changes

Add POSIX changes to release notes for Zephyr v3.2.

Signed-off-by: Chris Friedt <b335fc22cf1358c7e834a5788f93b9f24396b889@fb.com>

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