Add org.opencontainers.image labels to Docker image

[mueller-ma]

The Docker image could be labeled with a few org.opencontainers.image.* labels (https://github.com/opencontainers/image-spec/blob/main/annotations.md). These labels can be used by other tools, e.g. by Renovate to fetch changelogs when updating docker-compose or helm charts with RocketChat (https://docs.renovatebot.com/modules/datasource/docker/).