Correct the corpus size of DeReKo-KorAP-2026-II in the release notes

Use the figures the index actually reports (corpus statistics API):
31,469,333,310 tokens from 94,894,312 texts.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Change-Id: Ie765e1b3f096b895c3f944ecc7b8d0f28471100d
2 files changed