fix CNAME format warnings

The page build completed successfully, but returned the following warning for the `master` branch:

The CNAME `code.praqma.com/jenkinsascodereference` is not properly formatted. See https://help.github.com/articles/troubleshooting-custom-domains/#github-repository-setup-errors for more information.

I would like to have a dedicated domain for that, once we have it CNAME will be fixed 