[docs] [issue28107] Update typing module dicumentation for NamedTuple

[Ivan Levkivskyi]

Ivan Levkivskyi added the comment:

Guido,

> Honestly I think it's better if this remains a "hidden" feature until we have support for it in mypy. So let's wait for that.

This patch now could be applied (since the mypy PR for this is merged).

----------

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue28107>
_______________________________________