Changelog for release 0.9.1

Author: CohenCyril

Changelog.md

@@ -1,10 +1,13 @@
 # Changelog
 
-## Unreleased
+## [0.9.1] - 2020-06-03
 
 - `HB.instance` can be applied directly to a definition as in
   `HB.instance Definition foo := Bar.Build T ...`
 - port to coq-elpi version 1.4
+- Operations `op` from factory `f` are not bound to `f_op` anymore,
+  they are now bound to `op` and potentially masked operations
+  are accessible via `Super.op`.
 
 ## [0.9.0] - 2020-03-11