missing HexString documentation

[Ralph Doncaster]

On Wednesday, 7 February 2018 at 15:54:05 UTC, Ralph Doncaster 
wrote:
> Doesn't that go against the idea of -betterC, or will std.conv 
> work with -betterC.
>
> p.s. contrary to what the deprecation notice says, hex strings 
> are very often used in crypto/hashing test cases.  Most hash 
> specs have example hash strings to verify implementation code.

As expected,
auto data = cast(ubyte[]) x"deadbeef";
works with -betterC, but
auto data = cast(ubyte[]) hexString!"deadbeef";
does not.