Update RELEASES.md

Author: rflamary

RELEASES.md

@@ -6,7 +6,7 @@ This new release adds support for sparse cost matrices in the exact EMD solver.
 
 
 #### New features
-- Add support for sparse cost matrices in EMD solver (PR #778, Issue #397)
+- Add support for sparse cost matrices in exact EMD solver `ot.emd` and `ot.emd2` (PR #778)
 - Added Sliced OT plans (PR #767)
 
 #### Closed issues