docs: update stale FAQ prize timing reference

[ideals2201]

Addresses part of #199.

Issue: #199
Source checked: https://scrollprize.org/prizes and scrollprize.org/docs/34_prizes.md

Summary

• Update the FAQ dates answer to point readers to the current Open Prizes page.
• Keep the 2024 prize page linked as historical reference.

Why

Issue #199 tracks out-of-date documentation on scrollprize.org. The FAQ still says the team is evaluating 2024 submissions and preparing next stages, while the current docs have an active Open Prizes page.

Scope / Duplicate Check

This is intentionally limited to scrollprize.org/docs/09_faq.md.

I did not change the stale 7 x $60,000 prize-count wording because PR #1050 already addresses that part of #199 in 01_get_started.md and the landing page.

Verification

• Checked scrollprize.org/docs/34_prizes.md for id: prizes and the Open Prizes title.
• Ran git diff --check.
• Confirmed the stale preparing the next stages phrase is removed from scrollprize.org/docs/09_faq.md.

Notes

No historical prize archive pages were changed.

[vercel]

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