Example commands in README do not work. ZEPHYR_SDK_VERSION needed

[kunom]

Just tried to follow you build scripts to build images for SDK version 0.16.1 (...), which is not available as pre-built image. It failed with

+ docker build --build-arg BASE_IMAGE=zephyr:base-0.16.1-SDK --build-arg 'ZEPHYR_SDK_TOOLCHAINS=-t arm-zephyr-eabi' -f ./zephyr/Dockerfile -t zephyr:arm-0.16.1-SDK ./zephyr
[...]
1.451 /bin/sh: 1: /opt/toolchains/zephyr-sdk-1.0.0/setup.sh: not found

Please ignore the wrong tag names (thanks to Github Copilot).

But it turns out that the ZEPHYR_SDK_VERSION build argument is also needed for the images derived from the base image, not only for the base image itself.