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/frc971/control_loops/drivetrain/drivetrain_config.h b/frc971/control_loops/drivetrain/drivetrain_config.h
index 31c911a..8e0a58d 100644
--- a/frc971/control_loops/drivetrain/drivetrain_config.h
+++ b/frc971/control_loops/drivetrain/drivetrain_config.h
@@ -13,9 +13,7 @@
 #include "frc971/control_loops/state_feedback_loop_converters.h"
 #include "frc971/shifter_hall_effect.h"
 
-namespace frc971 {
-namespace control_loops {
-namespace drivetrain {
+namespace frc971::control_loops::drivetrain {
 
 // Configuration for line-following mode.
 struct LineFollowConfig {
@@ -236,8 +234,6 @@
     };
   }
 };
-}  // namespace drivetrain
-}  // namespace control_loops
-}  // namespace frc971
+}  // namespace frc971::control_loops::drivetrain
 
 #endif  // FRC971_CONTROL_LOOPS_DRIVETRAIN_CONSTANTS_H_