fixed a typo

NEWS.txt

@@ -4,7 +4,7 @@ Interface change:
  * tensor.grad(cost, wrt) will return an object of the "same type" of wrt.
    If wrt is a tensor variable, list or tuple, it will return the same thing.
    This is an interface change outside the normal release number scheme. We need
-   this for pylearn2 and waiting for a futur release is not a good solution.
+   this for pylearn2 and waiting for a future release is not a good solution.
 
 Know bug:
  * CAReduce with nan in inputs don't return the good output.