Update NEWS.txt

NEWS.txt

@@ -126,6 +126,8 @@ New features:
  * sparse_variable[M:N, O:P] now works (Li Yao, Frederic)
     * Warning: M, N, O, and P should be Python int or scalar tensor variables,
       in particular, None is not well-supported.
+ * tensor.tensordot can now be moved to GPU (Sander Dieleman, Pascal)
+
 
 New optimizations:
  * AdvancedSubtensor1 reuses preallocated memory if available (scan, c|py_nogc linker) (Frederic)