Issue 4556: cmp() function erroneously noted as gone in "What's New"

What's new in 3.0 documentation says cmp() function is gone, yet it 
isn't:

>>> sys.version_info; cmp(1,1); cmp(1,2); cmp(2,1)
(3, 0, 0, 'final', 0)
0
-1
1