Now users should create a symbolic link to docker-compose-ssl.yml if
they want to enable SSL or docker-compose-nossl.yml if not.
Rewrite README to describe this rule.
This fixes https://github.com/mattermost/mattermost-docker/issues/5.
Do not copy config.json into /matteronst/config directly because:
> Changes to a data volume will not be included when you update an image.
>
> -- https://docs.docker.com/engine/userguide/dockervolumes/
Instead copy config.template.json into the root and generate
/mattermost/config/config.json from the file.
