docs: clarify winnow fills the gap where manual Frigate training images are absent

CHANGELOG.md

@@ -11,7 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
-- **`MAX_AUTO_IMAGES` default lowered from `80` to `20`**: 20 diverse images is sufficient for Frigate's face recognition model; the previous default led to diminishing returns and longer runs.
+- **`MAX_AUTO_IMAGES` default lowered from `80` to `20`**: winnow is designed to fill the gap where manual Frigate training images don't exist — not to be the primary dataset. A conservative default ensures winnow-imported images remain secondary to hand-picked ones where both exist.
 
 ## [0.4.9] - 2026-06-14