[docs] Document bytecode changes in 3.6 (issue 28810)

[levkivskyi at gmail.com]

I have only one comment, otherwise the patch LGTM.


http://bugs.python.org/review/28810/diff/19372/Doc/library/dis.rst
File Doc/library/dis.rst (right):

http://bugs.python.org/review/28810/diff/19372/Doc/library/dis.rst#newcode980
Doc/library/dis.rst:980: pushes the return value.
I think it is not completely clear what happens with

f(*x, *y, **z, **w)

As I understand, there will be always at most one element on the stack
built with BUILD_MAP_UNPACK_WITH_CALL, and only one element built by
BUILD_TUPLE_UNPACK_WITH_CALL. The latter two are not documented yet. I
think it would make sense to also document them, and mention them here.

http://bugs.python.org/review/28810/