Docs feedback: Anchor scripts

https://docs.gitlab.com/ee/ci/yaml/yaml_optimization.html#yaml-anchors-for-scripts

The documentation about Anchor Script do not work. When i try to execute any job from the example, i always encounter FATAL: unsupported script.

I'm running it from local gitlab-runner v15 using gitlab-runner exec shell job1.

I tried to update the script following YAML cook book without success, so I have no idea about how to fix this issue.