doc/releases: release-notes-3.0: remove empty sections
doc/releases: release-notes-3.0: remove empty sections

Remove the empty sections.

Signed-off-by: Dan Kalowsky <9431e108b67d1efa9df54e6351da1951bcd9be32@deadmime.org>

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