use custom config.yml with docker

[nsecrist]

How can mount a file in a docker container to be used as the config.yml for webview?
Possibly related to #55.

I need to be able to update the base config so that context-path can be set.

docker-compose.yml

services:
    proxy:
         image: nginx:latest
         container_name: nginx
         volumes:
            - ./nginx.conf:/etc/nginx/nginx.conf
         ports:
            - "80:80"
         links:
            - kafka.webview

    kafka.webview:
        image: sourcelaborg/kafka-webview:latest
        container_name: kafka-webview
        volumes:
            - kafkawebview_data:/app/data
            - ./webview-config:{WHAT GOES HERE} # Not sure what goes here.
        expose:
            - "8080"

Any help here would be great. Thanks!