Add update-discussion documentation to safe-outputs reference

[Copilot]

The update-discussion safe output type was missing from the user-facing documentation despite being fully implemented and tested.

Changes

• Added table entry in "Available Safe Output Types" with anchor link to detailed section
• Added documentation section after "Close Discussion" covering:
  • Field enablement pattern (title:, body:, labels:)
  • Label restriction via allowed-labels
  • Target options (triggering, *, or specific number)
  • Cross-repository support via target-repo

Example

safe-outputs:
  update-discussion:
    title:                    # enable title updates
    body:                     # enable body updates
    labels:                   # enable label updates
    allowed-labels: [bug, idea] # restrict to specific labels
    max: 1                    # max updates (default: 1)
    target: "*"               # "triggering" (default), "*", or number
    target-repo: "owner/repo" # cross-repository

Documentation follows the established pattern used for update-issue and update-pull-request.

Original prompt

Udate docs safe output with update-discussion.

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[mnkiefer]

@copilot: Make sure documentation follow actual implementation.

[Copilot]

@copilot: Make sure documentation follow actual implementation.

I've verified the documentation against the actual implementation in pkg/workflow/update_discussion.go and actions/setup/js/update_discussion.cjs. The documentation accurately reflects all supported fields:

• Field enablement pattern (key existence for title:, body:, labels:)
• Label restriction via allowed-labels with implicit label enablement
• Inherited fields from UpdateEntityConfig (max, target, target-repo, github-token)
• Default values and behaviors

The documentation follows the same pattern as update-issue and matches the schema in frontmatter-full.md. All features are correctly documented.