[docs] Expand documentation about type aliases and NewType in the typing module (issue 27644)

[levkivskyi at gmail.com]

On 2016/07/30 00:33:29, gvanrossum wrote:

> I probably didn't think about this when
> reviewing the PEP text, so perhaps the PEP should also be updated.

This is already in the PEP, quote: "NewType accepts only one argument
that shoud be a proper class".

http://bugs.python.org/review/27644/