message: Document the OSL version for reference implementations
diff: This folder contains reference OSL implementations for the standard MaterialX nodes, documenting their intended functionality as of MaterialX v1.35.
  -The Open Shading Language team maintains source file generators for the MaterialX nodes at https://github.com/imageworks/OpenShadingLanguage/tree/master/src/shaders/MaterialX.
  +The Open Shading Language team maintains source file generators for the MaterialX nodes at https://github.com/imageworks/OpenShadingLanguage/tree/master/src/shaders/MaterialX, and these source files were built from [this version](https://github.com/imageworks/OpenShadingLanguage/tree/e9e55306ea7b4356b51c91c180e6e9ac1cad6bb1) of the repository.
  