message: calibration: add missing comment
diff: @@ -8,6 +8,10 @@ namespace dronecore {
  class CalibrationImpl;
  class System;
  +/**
  + * @brief The Calibration class enables to calibrate sensors of a drone such
  + * as gyro, accelerometer, and magnetometer.
  + */
  class Calibration : public PluginBase {
  public:
  /**
  