State clearly that this is a 3-clause BSD

README

@@ -5,6 +5,9 @@ Kokkos is designed to target complex node architectures with N-level memory
 hierarchies and multiple types of execution resources. It currently can use
 OpenMP, Pthreads and CUDA as backend programming models.
 
+Kokkos is licensed under standard 3-clause BSD terms of use. For specifics
+see the LICENSE file contained in the repository or distribution.
+
 The core developers of Kokkos are Carter Edwards and Christian Trott
 at the Computer Science Research Institute of the Sandia National
 Laboratories.