metadata v2.1 notes: assay_type of 6 ISS samples changed (correction of the changelog)

metadata/v2/README.md

@@ -127,5 +127,5 @@ repository:
 
 - **2.1** (tag `metadata-v2.1-20261105`): each assay now has one name (for example "Resolve Molecular Cartography"
   became "Molecular Cartography", and "Visium (FFPE)" became "Visium", since preservation is its own field).
-  `um_per_unit` and `image_um_per_px` are copied exactly from the release parquet. No annotation changed.
+  `um_per_unit` and `image_um_per_px` are copied exactly from the release parquet. Organ, tissue, disease, life stage and the other annotations did not change. One derived field did: `assay_type` of the 6 ISS (Cartana) samples of GSE227046 is now imaging-based (it was sequencing-based).
 - **2.0** (tag `metadata-v2-20261105`): first release.