docs(v2): add explicit 2-hour kline window semantics for k0-k5

v2/README_v2_release.md

@@ -21,3 +21,16 @@ This V2 release contains the finalized trading-layer tables used for modeling.
 - Time cutoff: pre80m
 - User-market cap: 30
 - Markets included: only price-covered markets
+
+## Kline window semantics (2-hour bins)
+
+For the final modeling table (`v2_behavior_features_merged_pospnl_kline_v1.parquet`), Kline features are computed in rolling pre-trade windows with 2-hour width:
+
+- `k0_*`: 0–2 hours before trade
+- `k1_*`: 2–4 hours before trade
+- `k2_*`: 4–6 hours before trade
+- `k3_*`: 6–8 hours before trade
+- `k4_*`: 8–10 hours before trade
+- `k5_*`: 10–12 hours before trade
+
+Each window includes: `open`, `high`, `low`, `close`, `points`, `avg`.