Fixing "The unauthenticated git protocol on port 9418 is no longer supported." when running install_env.sh in docker container

[btschwertfeger]

To fix this issue you could add the following line:

git config --global url."https://github.com/".insteadOf git://github.com/

to /Hands-On-Machine-Learning-with-CPP/env_scripts/README.md where you start the docker container for the first time.