[CG Stewardship] Publish stewardship roadmap to Confluence

[laurabelinfante]

Summary

Publish the community stewardship roadmap (second tab) to Confluence. This should happen after issue #513 is completed (ADR published to commongrants.org) so the Confluence roadmap can cross-link to the published ADR.

Acceptance criteria

• The stewardship roadmap content from the Google Doc's "Roadmap" tab is published to Confluence
• The Confluence page cross-links to the published stewardship ADR on commongrants.org