v1.6.0

Release notes

Added

• zsh image-type to the ncs-zephyr Docker image. This image-type is based on the devand contains
  ZSH shell and some other tools for nicer developer experience.

Changed

• ncs-zephyr Docker image now adds environment variables of the toolchain-manager to the bashrc file
  to provide access to the installed tools. Previously that was done by the ENTRYPOINT command,
  however that approach didn't always work with VSCode's Dev Containers.