docs(gitlab): Add coloring info (#27907)

Signed-off-by: Stavros Ntentos <133706+stdedos@users.noreply.github.com>
Co-authored-by: HonkingGoose <34918129+HonkingGoose@users.noreply.github.com>

lib/modules/platform/gitlab/readme.md

@@ -36,6 +36,9 @@ If you're using a private [GitLab container registry](https://docs.gitlab.com/ee
 - Make sure the user that owns the `RENOVATE_TOKEN` PAT is a member of the corresponding GitLab projects/groups with the right permissions.
 - Make sure the `RENOVATE_TOKEN` PAT has the `read_registry` scope.
 
+You may want to set `FORCE_COLOR: 3` or `TERM: ansi` to the job, in order to get colored output.
+[GitLab Runner runs the container’s shell in non-interactive mode, so the shell’s `TERM` environment variable is set to `dumb`.](https://docs.gitlab.com/ee/ci/yaml/script.html#job-log-output-is-not-formatted-as-expected-or-contains-unexpected-characters)
+
 ## Features awaiting implementation
 
 - The `automergeStrategy` configuration option has not been implemented for this platform, and all values behave as if the value `auto` was used. Renovate will accept the Merge Request without further configuration, and respect the strategy defined in the Merge Request, and this cannot be overridden yet