Zephyr-sdk-install-and-config

Steps to installing Zephyr SDK and prerequisites in the context of NordicSemi's forked branch of Zephyr, and specifically details on `west init`, `west zephyr-export` and `west update`:

• https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/getting_started/index.html#getting-started

Instructions to install Zephyr SDK 0.13.0, note this is a Zephyr website page:

• https://docs.zephyrproject.org/latest/getting_started/installation_linux.html

Back to Nordic, their instructions for installing Segger Embedded Studio for Nordic development:

• https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/gs_installing.html