docs: musicgen has no per-track sidecar JSON (folder tree fix)

README.md

@@ -161,7 +161,8 @@ suno = load_dataset("mippia/HAIM", "A2_fake_links_preview", split="suno")
 │   │   ├── sonics/real_songs.csv       # 48,090 YouTube links
 │   │   └── mtg_tracks.csv
 │   └── A2_fake
-│       ├── acestep/  musicgen/  lyria-pro3/        # audio + sidecar JSON + metadata.csv
+│       ├── acestep/  lyria-pro3/                   # audio + sidecar JSON + metadata.csv
+│       ├── musicgen/                               # audio + metadata.csv (no sidecar)
 │       └── suno[.json|_tracks.csv]  udio…  mureka…  # link manifests
 ├── B_hybrid
 │   ├── B1…B4, B6…B9/                   # audio + metadata.csv