samples: hci_uart: Add references to sections
samples: hci_uart: Add references to sections

Add a couple of references so that we can link to those from other
documentation sections.

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

ldts/zephyr,GiulianoFranchetto/zephyr,galak/zephyr,explora26/zephyr,zephyriot/zephyr,ldts/zephyr,GiulianoFranchetto/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,GiulianoFranchetto/zephyr,nashif/zephyr,nashif/zephyr,GiulianoFranchetto/zephyr,punitvara/zephyr,galak/zephyr,mbolivar/zephyr,zephyriot/zephyr,Vudentz/zephyr,kraj/zephyr,explora26/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,mbolivar/zephyr,ldts/zephyr,mbolivar/zephyr,finikorg/zephyr,ldts/zephyr,kraj/zephyr,punitvara/zephyr,finikorg/zephyr,punitvara/zephyr,galak/zephyr,Vudentz/zephyr,explora26/zephyr,mbolivar/zephyr,punitvara/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,zephyriot/zephyr,nashif/zephyr,nashif/zephyr,Vudentz/zephyr,finikorg/zephyr,explora26/zephyr,punitvara/zephyr,zephyriot/zephyr,Vudentz/zephyr,explora26/zephyr,zephyrproject-rtos/zephyr,mbolivar/zephyr,zephyriot/zephyr,kraj/zephyr,finikorg/zephyr,GiulianoFranchetto/zephyr,nashif/zephyr,Vudentz/zephyr,finikorg/zephyr,kraj/zephyr,ldts/zephyr,kraj/zephyr,zephyrproject-rtos/zephyr