Remove invalid '-D' 'docker run' argument

[jalessio]

According to the Docker run reference documentation, -D is not a valid argument for docker run.

I am noting that there is a lowercase -d argument, but it's not clear to me if that's what is intended here so I'm proposing just removing the invalid argument from the documentation for this project.

[leeroybrun]

Thank you for pointing this out. I replaced the -D argument by -d, as this is used to run the container in detached mode and to automatically stop the container once the command has finished executing.