Add a section in the specification to document fundamental aspects of the OpenCL API

Some design elements of the OpenCL API are central to the API philosophy and likely ought to be documented as such in the OpenCL specification. Here are a few examples that came up in recent discussion:

- Reference counting of objects
- Thread-safety requirements

Review the OpenCL specification sources and existing sections covering reference counting and thread-safety. Determine how these central API principles should be organized and documented, then verify that both listed aspects are addressed consistently in the specification.

Written by the indexing model from the issue text.