Point agent setup CTA to the setup docs

[nidhi-singh02]

Summary

• Link the “Read docs” action beside “Set up with your agent” directly to the matching setup section.
• Leave the site-wide and CLI documentation links pointed at the docs root.

Test plan

• bun run format:check
• bun run lint
• bun run typecheck
• bun run test
• bun run --cwd apps/marketing typecheck
• bun run --cwd apps/marketing build
• Verified locally that the CTA resolves to https://executor.sh/docs#set-up-with-your-agent with no browser console errors.