Added note about updating DOCKER_REPOSITORY in gitlab-ci.yml in new service docs
Added note about updating DOCKER_REPOSITORY in gitlab-ci.yml in new service docs

Changelog: None

Signed-off-by: Maciej Tomczuk <47d023a2c6aa0f95f3ba59401576525817621fac@northern.tech>

mendersoftware/meta-mender-qemu