extern(C++) documentation missing

[Manu]

Compare:
https://dlang.org/phobos/core_stdcpp_new_.html
and:
https://github.com/dlang/druntime/blob/master/src/core/stdcpp/new_.d

There's a lot of doco missing. The stuff wrapped in `extern(C++)`, and
also the bits in the `static if()` blocks.

Check out, https://dlang.org/phobos/core_stdcpp_array.html (and friends)
There's nothing there at all!

Anyone know what's the story here?
Hard to use a lib when the doco's empty.