Document File::Glob::csh_glob

Document File::Glob::csh_glob

In <https://rt.cpan.org/Ticket/Display.html?id=72021>, Damian Con-
way writes:

> PS: List::Maker previously followed the documented behaviour of
>     File::Glob, rather than the actual behaviour. So there's arguably a
>     bug in File::Glob as well. ;-)

List::Maker was forwarding calls to File::Glob::bsd_glob from its
global override in scopes where its override did not apply.  The
File::Glob documentation was misleading and implied that that was the
correct thing to do.