message: Finalize changelog for v1.38.5
diff: # Change Log
  -## [1.38.5] - Development
  +## [1.38.5] - 2022-07-09
  ### Added
  - Added a [refraction approximation](https://github.com/AcademySoftwareFoundation/MaterialX/pull/918) for transmissive surfaces in GLSL, selected by the hwTransmissionRenderMethod generator option.
  