Update changelog

CHANGELOG.md

@@ -7,12 +7,13 @@
 ### Added
 Features
 * `caculate_moments` method in `Meta_Model` class for a general calculation of the moments 
-* `PCEGPR` Class for combining polynomial chaos and gaussian processes 
+* `PCEGPR` class for combining polynomial chaos and gaussian processes 
 
 Tests
-* Tests for `GPE` Class 
+* Tests for `GPE` class 
 * Tests for `calculate_moments` method in `Meta_Model` and `GPESkl` classes 
-* Tests for `PCEGPR` Class 
+* Tests for `PCEGPR` class 
+* Tests for `PostProcessing`class
 
 Examples
 * Example `analytical_function_pcegpr` to show application of the combined class `PCEGPR`
@@ -21,6 +22,8 @@ Examples
 * Split surrogate classes into template class `MetaModel` and child classes `PCE` and `GPESklearn`
 * Changed Exception format in `GPE` class to more specific Exceptions 
 * Extend `Inputs.add_marginals` to allow direct setting of marginal properties
+* Move Sobol' calculation to `PCE.calculate_sobol`
+* Clean `PostProcessing` class and update for general `MetaModel` objects
 
 Bug fixes
 * `ExpDesign` always uses user-defined samples when given