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

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#newcode98... 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/