message: add simple description of set_num_threads()
diff: @@ -294,4 +294,12 @@ class Interpreter(object):
  return self._interpreter.ResetVariableTensors()
  def set_num_threads(self, i):
  + """Set number of threads used by TFLite kernels.
  +
  + If not set, kernels are running single-threaded. Note that currently,
  + only some kernels, such as conv, are multithreaded.
  +
  + Args:
  + i: number of threads.
  + """
  return self._interpreter.SetNumThreads(i)
  