CodeQuality job definition is only working for GitLab >= 10.4

As per the discussion on Slack: https://gitlab.slack.com/archives/C0AR2KW4B/p1532349500000109, it appears our doc isn't mentioning anywhere that the job definition will work only for GitLab >=10.4. As the documentation is not versioned, we should either:

  • Add a note about deprecation, and provide the previous job definition for old instances.
  • Tag the 10-4-stable image with 10-3-stable, 10-2-stable and so on.

/cc @bikebilly

Edited by Philippe Lafoucrière