[codex] docs: add savings alias route

[ketpatil77]

Description

The docs site was 404ing on /docs/savings, so this adds a short alias page that points users at the existing community savings content.

Changes Made

• Added docs/content/docs/savings.mdx as an alias route.
• Added savings to the docs nav metadata.

Testing

• Reviewed the route and meta diff for the new docs page.
• Confirmed the alias points to existing community-savings and metrics pages.

Impact

/docs/savings now resolves on the docs site instead of 404ing.

[github-actions]

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