[docs] [issue16701] Docs missing the behavior of += (in-place add) for lists.

R. David Murray added the comment: Wording looks ok...except that technically it is not that 'n' is an integer, it's that 'n' can play the role of an integer (ie: it has an __index__ method). ---------- _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue16701> _______________________________________