Add instructions for how to run via Docker when someone asks for it

[sorenlouv]

Removed the Docker section from the readme because no-one seems to use it

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Run via Docker

If you don't have Node.js or git installed locally, you can run backport via Docker.

Click to expand

The easiest way is to add the following snippet to your bash profile:

backport() {
    BACKPORT_CONFIG_DIR=~/.backport
    GIT_CONFIG_FILE=~/.gitconfig

    docker run -it --rm -v $(pwd):/app:ro -v $BACKPORT_CONFIG_DIR:/root/.backport -v $GIT_CONFIG_FILE:/etc/gitconfig sqren/backport "$@"
}

Where:

• BACKPORT_CONFIG_DIR: This can be ANY empty folder on your local machine. Upon running the docker container for the first time, a config.json will be created automatically. This must be filled out with username and accessToken or these must be passed as CLI arguments: backport --username <username> --accessToken <accessToken>
• GIT_CONFIG_FILE: Must point to a local .gitconfig file that contains the user's name and email.

You can now use backport as if it was installed on the host machine.