message: Add a intro comment to SimpleExample
diff: @@ -37,6 +37,8 @@ DEFINE_int32(num_readouts, 100,
  namespace minigo {
  namespace {
  +// Demonstrates how to perform basic self-play, while eliding the additional
  +// complexity required by the training pipeline.
  void SimpleExample() {
  // Determine whether ANSI color codes are supported (used when printing
  // the board state after each move).
  