Standalone dataset card; drop constant column; clarify animated_joints

NOTICE.md

@@ -41,8 +41,8 @@ responsibility as the user of the asset, not something this repository can settl
 ## Purpose of this mirror
 
 The collection is published to support reproducible research on skeletal animation and motion
-generation, as the raw source pool behind the `UniML3D` dataset. It is a convenience copy of
-material that is already publicly indexed; it adds no rights and removes none.
+generation. It is a convenience copy of material that is already publicly indexed; it adds no
+rights and removes none.
 
 ## Requests for removal