Update CHANGELOG.md with changes in the optimisation topic

CHANGELOG.md

+### v0.4.1 ###
+** Optimisation - Memetic Algorithm**\
+\* Update `mutPop()` to use the parallel for-loop (`parfor`) whenever it is available.\
+\* Update `selParents()` to use the parallel for-loop (`parfor`) whenever it is available.
+
+-------------------------------------------
+
+
 ### v0.4 ###
 **Utilities - Generic**\
 \* Change the interface of `rotMat3d()`, so that the last argument is a boolean (`logical` in MATLAB), declaring whether the given angles are in degrees (if false, the angles are treated as radians). This is a **backwards incompatible** change.\