Finalize changelog for v1.38.6

Author: jstone-lucasfilm

CHANGELOG.md

@@ -1,6 +1,6 @@
 # Change Log
 
-## [1.38.6] - Development
+## [1.38.6] - 2022-11-04
 
 ### Added
 - Added new [Unified Noise](https://github.com/AcademySoftwareFoundation/MaterialX/pull/1087), [Color Correct](https://github.com/AcademySoftwareFoundation/MaterialX/pull/1086), and [Bump](https://github.com/AcademySoftwareFoundation/MaterialX/pull/1085) nodes, providing artistic interfaces over the standard procedural, adjustment, and geometric primitives.
@@ -16,6 +16,8 @@
 ### Changed
 - Improved the alignment of the [UsdPreviewSurface shading graph](https://github.com/AcademySoftwareFoundation/MaterialX/pull/1082) with reference implementations.
 - Improved the accuracy of the [thin-film BSDF](https://github.com/AcademySoftwareFoundation/MaterialX/pull/1055) implementation in GLSL.
+- Improved code generation for the [mix](https://github.com/AcademySoftwareFoundation/MaterialX/pull/1104) node of 'surfaceshader' type.
+- Removed [add and multiply](https://github.com/AcademySoftwareFoundation/MaterialX/pull/1089) nodes for 'surfaceshader', 'volumeshader', and 'displacementshader' types.
 - Refactored and extended the [Advanced Options](https://github.com/AcademySoftwareFoundation/MaterialX/pull/1093) panel in MaterialXView.
 
 ### Fixed