[C++-sig] How to use make_default with keyword expression

[Johan Råde]

The documentation of boost::python::make_constructor should be fixed.
It shows the synopsis:

     template <class T, class ArgList, class Generator>
     object make_constructor();

     template <class ArgList, class Generator, class Policies>
     object make_constructor(Policies const& policies);

This is obviously not correct.