Description of `CI_COMMIT_BEFORE_SHA` does not mention that it is also zeros for scheduled pipelines

In the Predefined CI/CD variables reference docs page, the description for CI_COMMIT_BEFORE_SHA is the following:

The previous latest commit present on a branch or tag. Is always 0000000000000000000000000000000000000000 for merge request pipelines, the first commit in pipelines for branches or tags, or when manually running a pipeline.

The description should mention that the value is also 0000000000000000000000000000000000000000 for scheduled pipelines.