Nest some more namespaces

Did someone previously suggest that all namespace had been
nested?  Silly.

Signed-off-by: Stephan Pleines <pleines.stephan@gmail.com>
Change-Id: I22278c1caaeba8b47dc46fb2ed3078c20a11e190
diff --git a/y2020/vision/camera_reader.h b/y2020/vision/camera_reader.h
index 9a8cf6f..81dfa1a 100644
--- a/y2020/vision/camera_reader.h
+++ b/y2020/vision/camera_reader.h
@@ -17,8 +17,7 @@
 #include "y2020/vision/sift/sift_training_generated.h"
 #include "y2020/vision/tools/python_code/sift_training_data.h"
 
-namespace frc971 {
-namespace vision {
+namespace frc971::vision {
 
 class CameraReader {
  public:
@@ -170,6 +169,5 @@
       new frc971::vision::SIFT971_Impl()};
 };
 
-}  // namespace vision
-}  // namespace frc971
+}  // namespace frc971::vision
 #endif  // Y2020_VISION_CAMERA_READER_H_