doc: Add reference labels in getting started doc
doc: Add reference labels in getting started doc

Add reference labels in getting_started/index.rst

Signed-off-by: Uma Praseeda <2e595cf83483dc8d7bd7ef76bf6655073171a4b1@nordicsemi.no>

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