Add example non-default env variables

[Jafner]

It would be useful to me to see an example of one way the proxy could be configured with env variables.

My understanding is that to explicitly grant the proxy access to SECRETS, I would add the line -e SECRETS=1 to the Docker run command, or - SECRETS=1 to the environment block of my docker-compose.yml.

The system is pretty simple and intuitive, but I think basic security practices like this should be as approachable and accessible as possible.

An example docker-compose.yml file would also be useful, perhaps with commented modification env variables.