Setup guide completeness

Forking the discussion from https://github.com/renovatebot/renovate/issues/7843

Following the setup guide left me with an incomplete CI configuration (see rundown).

• created a new blank project
• added a .gitlab-ci.yml with

include:
  - project: 'renovate-bot/renovate-runner'
    file: '/templates/renovate.gitlab-ci.yml'

• set the RENOVATE_TOKEN CI var

Result of starting the CI is just

The form contains the following error: No stages / jobs for this pipeline.

Adding stages: [deploy] as suggested did not change anything.

What's missing to make it work? Thanks