doc: Document the new native Windows dev environment
doc: Document the new native Windows dev environment

The new native Windows development environment no longer relies on MSYS2
or WSL at all. Instead it uses a standard Command Prompt and Windows
native tools. Document the installation and setup process in order to be
able to compile and develop.

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

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