Update v2.1.0.md

docs/releases/v2.1.0.md

 # v2.1.0
 
+1 April 2020
+
 ## New features:
 
 - Region search also searches for relatedAreas
@@ -10,7 +12,6 @@
 - (Re)allow the preview pane to be dragged around
 - Slight tweak to UI, allow for better side navigation bar rendering
 - Allow registered volume to be displayed on top of reference templates
-- Added DiFuMo atlases
 - Allow for bulk download of favourited datasets
 - Added ability to copy URL directly