Auto-sync: Update Chinese docs from English PR

Synced from: pingcap/docs#22497
Target PR: pingcap#21394
AI Provider: gemini

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: github-actions[bot]

keywords.md

@@ -67,6 +67,7 @@ TiDB 从 v7.5.3 和 v7.6.0 开始提供 [`INFORMATION_SCHEMA.KEYWORDS`](/informa
 - ADMIN
 - ADVISE
 - AFTER
+- AFFINITY
 - AGAINST
 - AGO
 - ALGORITHM
@@ -674,6 +675,7 @@ TiDB 从 v7.5.3 和 v7.6.0 开始提供 [`INFORMATION_SCHEMA.KEYWORDS`](/informa
 - STATS_BUCKETS
 - STATS_COL_CHOICE
 - STATS_COL_LIST
+- STATS_DELTA
 - STATS_EXTENDED
 - STATS_HEALTHY
 - STATS_HISTOGRAMS