missing HexString documentation

[Adam D. Ruppe]

On Wednesday, 7 February 2018 at 16:03:17 UTC, Ralph Doncaster 
wrote:
> As expected,
> auto data = cast(ubyte[]) x"deadbeef";
> works with -betterC, but
> auto data = cast(ubyte[]) hexString!"deadbeef";
> does not.

That's just because -betterC is buggy and extremely incomplete 
(this is why I'm so annoyed that it is getting advertised, it is 
nowhere near ready for use). there's no reason why it shouldn't 
work once those bugs get fixed.