Missing env vars in docker run command

[muety]

In README.md there is the following command:

docker run --it  --name tgr -p 5000:5000 -e CLIENT_ID="xxxxxxx" -e CLIENT_SECRET="xxxxxxxxxxxxxxx" -e DEBUG="True" tgr

There is two issues with that:

1. It should be -it, rather than --it, since the first one is invalid
2. You also need to specify -e HOST="0.0.0.0" and -e PORT="5000" in order for the app to start.

Additionally, you might want to add:

1. --rm flag
2. When not explicitly passing a value for the env parameters (e.g. just -e CLIENT_ID) the values from the user's local environment are being used, which might be preferable (because easier), since the user sourced the .env file before anyway.