message: [ci] fix readme command
  Deleted . by mistake
diff: @@ -56,7 +56,7 @@ zsh is only needed to debug and work on `build_boost.zsh` locally.
  To create the image, start in the directory containing this README and run:
  - $ docker build --no-cache -t bond-ubuntu-1804 --build-arg UBUNTU_VERSION="18.04"
  + $ docker build --no-cache -t bond-ubuntu-1804 --build-arg UBUNTU_VERSION="18.04" .
  This will make the Docker image with all the required dependencies and will
  compile all the required versions of Boost (using the `build_boosts.zsh`
  