Updating changelog with correct categorizations (#393)

CHANGELOG.md

@@ -4,14 +4,15 @@ Full documentation for rocRAND is available at [https://rocrand.readthedocs.io/e
 
 ## (Unreleased) rocRAND-x.x.x for ROCm 6.0.0
 ### Changed
-- Removed hipRAND submodule from rocRAND. hipRAND is now only available as a separate package.
 - Generator classes from `rocrand.hpp` are no longer copyable, in previous versions these copies
 would copy internal references to the generators and would lead to double free or memory leak errors.
   These types should be moved instead of copied, and move constructors and operators are now defined
-  for them. 
+  for them.
+### Optimized  
 - Improved MT19937 initialization and generation performance.
+### Removed
+- Removed hipRAND submodule from rocRAND. hipRAND is now only available as a separate package.
 - Removed references to and workarounds for deprecated hcc
-
 ### Fixed
 - `mt19937_engine` from `rocrand.hpp` is now move-constructible and move-assignable. Previously the
 move constructor and move assignment operator was deleted for this class.