No documentation for core.sys?

[Shriramana Sharma via Digitalmars-d-learn]

In my recent search for D's equivalent of isatty, I found out that there is 
a core.sys.posix module only by rgrepping under /usr/include/dmd. Why isn't 
there a documentation page http://dlang.org/phobos/core_sys.html whereas 
lots of other core.* modules are documented?

-- 
Shriramana Sharma, Penguin #395953