Fix example for itertools.count().

Doc/library/itertools.rst

@@ -237,7 +237,7 @@ loops that truncate the stream.
 
       def count(start=0, step=1):
           # count(10) --> 10 11 12 13 14 ...
-          # count(2.5, 0.5) -> 3.5 3.0 4.5 ...
+          # count(2.5, 0.5) -> 2.5 3.0 3.5 ...
           n = start
           while True:
               yield n