Changed formating of the not_fn proposal.

Moved the document number and the author contact information
to header of the document to meet formal constrains.
Changed formating of the proposed standarized text - use stdins
tag instead of std.
Allow move-only types for not_fn.

The previous wording requires the wrapped callable object to be
copy constructible without any reason. The code is now chaged
to accept move-only types.
Fixed link to the lambda proposal.

Fixed link to the "Generic Lambda" proposal. Changed formating
of INVOKE and cv.
Added missing throws caluse to not_fn.
Added remarks clause.
Added changes to 20.10/2 section.