Tabulate documentation map

[version-1]

Tabulate the documentation map

Summary

Make the Overview documentation map easier to scan by presenting it as a table and add the Agent Tutorial entry.

主な変更点:

• Replace the prose documentation map with a six-row table.
• Add Agent Tutorial to the English overview.
• Synchronize the Japanese overview with localized table descriptions.
• Point both README Documentation sections to the published documentation site.
• Remove the duplicated README Development sections.

チケットへのリンク

ここはまだない

やったこと

• Added the Agent Tutorial path at /getting-started/agent-tutorial.
• Described when to use QuickStart, Agent Tutorial, Setup Guide, Concepts, Guides, and Reference.
• Simplified the English and Japanese README documentation entry points to their locale-specific sites.

動作確認

• npm --prefix docs/site run build
• git diff --check
• Confirmed the Agent Tutorial entry and both table headers are present.
• Confirmed the README Documentation sections link to the expected locale sites and no Development heading remains.

レビュー & 動作確認 チェックリスト

• English map - Confirm all six entries render as a table on the overview page.
• Japanese map - Confirm the localized table renders with the same links.
• Agent Tutorial - Confirm the new entry opens /getting-started/agent-tutorial.
• README documentation - Confirm both README Documentation links open the expected site locale.

推奨テスト計画:

1. Open the English and Japanese Overview pages.
2. Confirm the documentation map is a table.
3. Follow the Agent Tutorial link in each locale.

その他気になることや相談ごと

特になし

Requested by: @version-1