doc: release notes: Add BLE controller to the highlights
doc: release notes: Add BLE controller to the highlights

Include the fact that the Zephyr BLE Controller is ready for
qualification in the release highlights.

Signed-off-by: Carles Cufi <853081dc8dca4fe6a7e3c984752718b5db36e060@nordicsemi.no>

aceofall/zephyr-iotos,kraj/zephyr,fbsder/zephyr,mbolivar/zephyr,explora26/zephyr,Vudentz/zephyr,finikorg/zephyr,runchip/zephyr-cc3220,kraj/zephyr,GiulianoFranchetto/zephyr,zephyrproject-rtos/zephyr,explora26/zephyr,Vudentz/zephyr,GiulianoFranchetto/zephyr,Vudentz/zephyr,kraj/zephyr,finikorg/zephyr,kraj/zephyr,finikorg/zephyr,fbsder/zephyr,explora26/zephyr,Vudentz/zephyr,Vudentz/zephyr,punitvara/zephyr,punitvara/zephyr,zephyrproject-rtos/zephyr,mbolivar/zephyr,kraj/zephyr,mbolivar/zephyr,fbsder/zephyr,galak/zephyr,zephyriot/zephyr,aceofall/zephyr-iotos,runchip/zephyr-cc3220,nashif/zephyr,zephyrproject-rtos/zephyr,explora26/zephyr,zephyriot/zephyr,zephyrproject-rtos/zephyr,runchip/zephyr-cc3220,finikorg/zephyr,punitvara/zephyr,finikorg/zephyr,ldts/zephyr,ldts/zephyr,explora26/zephyr,zephyriot/zephyr,nashif/zephyr,ldts/zephyr,zephyriot/zephyr,fbsder/zephyr,nashif/zephyr,galak/zephyr,GiulianoFranchetto/zephyr,mbolivar/zephyr,aceofall/zephyr-iotos,GiulianoFranchetto/zephyr,runchip/zephyr-cc3220,mbolivar/zephyr,punitvara/zephyr,nashif/zephyr,runchip/zephyr-cc3220,aceofall/zephyr-iotos,zephyrproject-rtos/zephyr,zephyriot/zephyr,fbsder/zephyr,GiulianoFranchetto/zephyr,punitvara/zephyr,Vudentz/zephyr,galak/zephyr,ldts/zephyr,nashif/zephyr,galak/zephyr,ldts/zephyr,galak/zephyr,aceofall/zephyr-iotos