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/peripheral/uart_buffer.h b/motors/peripheral/uart_buffer.h
index 9266465..714cfe8 100644
--- a/motors/peripheral/uart_buffer.h
+++ b/motors/peripheral/uart_buffer.h
@@ -6,8 +6,7 @@
 
 #include "absl/types/span.h"
 
-namespace frc971 {
-namespace teensy {
+namespace frc971::teensy {
 
 // Manages a circular buffer of data to send out.
 template <int kSize>
@@ -90,7 +89,6 @@
   ++size_;
 }
 
-}  // namespace teensy
-}  // namespace frc971
+}  // namespace frc971::teensy
 
 #endif  // MOTORS_PERIPHERAL_UART_BUFFER_H_