message: Add kit docs for environmentSetupScript
diff: @@ -134,6 +134,10 @@ The following additional options may be specified:
  > A JSON object of key-value pairs specifying additional environment variables to be defined when using this kit.
  +`environmentSetupScript`
  +
  +> The absolute path to a script that modifies/adds environment variables for the kit. Uses `call` on Windows and `source` in `bash` otherwise.
  +
  ## Next steps
  - Explore the [CMake Tools documentation](README.md)
  