[docs] tuple or struct_time

[Alexander Belopolsky]

Functions in the time module that expect broken down time are
currently documented as accepting "tuple or struct_time".  For
example,

http://docs.python.org/py3k/library/time.html#time.strftime

However, in recent versions, ".. or struct_time" is redundant because

>>> issubclass(time.struct_time, tuple)
True

I think it would be more informative for a reader to change "tuple or
struct_time" to "9-tuple".