Update CHANGELOG.md

Author: AdrianSosic

CHANGELOG.md

@@ -33,6 +33,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `SubspaceDiscrete.from_product` and `SubspaceDiscrete.from_simplex` now split
   their `constraints` argument into filtering constraints (applied during construction)
   and batch constraints (stored in `batch_constraints`)
+- Internal search space and recommender logic simplified by reducing indirection and
+  argument passing between methods
 
 ### Fixed
 - Deserialization with constructor selection now correctly respects converter settings