NEWS: Add bullet about MPI C++ bindings

Signed-off-by: Jeff Squyres <jsquyres@cisco.com>

NEWS

@@ -80,6 +80,10 @@ Master (not on release branches yet)
 - Many enhancements to MPI RMA.  Open MPI now maps MPI RMA operations
   on to native RMA operations for those networks which support this
   capability.
+- The MPI C++ bindings -- which were removed from the MPI standard in
+  v3.0 -- are no longer built by default and will be removed in some
+  future version of Open MPI.  Use the --enable-mpi-cxx-bindings
+  configure option to build the deprecated/removed MPI C++ bindings.
 - ompi_info now shows all components, even if they do not have MCA
   parameters.  The prettyprint output now separates groups with a
   dashed line.