When publishing this spec on the OpenGL ES registry, Jon Leech noticed
that it didn't actually mention what the ES dependencies and
interactions were. I looked at extensions_table.h and noted that we
expose it in ES 3.0 contexts, and he added the obvious spec texts.
The updated copy also contains our official extension number.
https://github.com/KhronosGroup/OpenGL-Registry/issues/3
Acked-by: Matt Turner <mattst88@gmail.com>