message: Finalize changelog for v1.38.6
diff: # 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.
  ### 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
  