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/motors/seems_reasonable/spring.h b/motors/seems_reasonable/spring.h
index 90c9cd1..0847b3c 100644
--- a/motors/seems_reasonable/spring.h
+++ b/motors/seems_reasonable/spring.h
@@ -3,8 +3,7 @@
 
 #include <cmath>
 
-namespace motors {
-namespace seems_reasonable {
+namespace motors::seems_reasonable {
 
 float NextGoal(float current_goal, float goal);
 float PreviousGoal(float current_goal, float goal);
@@ -104,7 +103,6 @@
   float last_error_ = 0.0f;
 };
 
-}  // namespace seems_reasonable
-}  // namespace motors
+}  // namespace motors::seems_reasonable
 
 #endif  //  MOTORS_SEEMS_REASONABLE_SPRING_H_