ci: enable scheduled release PR merging for Documents

[marvinctl]

Type of change(s)

• Infrastructure / tooling (CI, build, deps, tests)

What changed and why

• Add Documents to the scheduled release-PR merge list alongside Calendar.
• Keep the fortnightly Saturday schedule, release branch and author filter, squash merging, required checks and repository protections unchanged.
• No app code, changelog, rollout configuration or GitHub settings change.

Tests performed

• YAML parsing, Bash syntax checks and git diff --check passed.
• Offline mocked runs checked scheduled selection (Calendar and Documents), manual Documents selection, and manual all-repository selection. The release author filter and --squash --auto arguments stayed unchanged; no real PR was merged.

Checklist

• I have self-reviewed my pull request.
• I understand every change in this pull request.
• Device testing and a changelog entry are not applicable to this workflow-only change.

[naveensingh]

Verbosity isn't a virtue, Marvin.