[Docs] Fix changelog for 3.9.1.

Signed-off-by: Giacomo Marciani <mgiacomo@amazon.com>

Author: gmarciani

CHANGELOG.md

@@ -5,8 +5,7 @@ CHANGELOG
 ------
 
 **BUG FIXES**
-- Fix an issue that may cause data loss when a shared storage is unmounted as part of a cluster update 
-  and no backup strategy is in place.
+- Remove recursive deletion of shared storage mountdir when unmounting filesystems as part of update-cluster operation.
 
 3.9.0
 ------