message: groups.md: Add gyroscope (gyro) as a separate category
  Previously, gyroscope were lumped in with compasses (magnetometers).
  This isn't really proper as a gyroscope measures rotation rates in a
  given axis, and has nothing to do with a magnetometer's use case.
diff: @@ -81,7 +81,7 @@ and is not meant to be installed anywhere.
  @brief Light sensors with special function: Color recognition
  -@defgroup compass Compass/Gyro/Magnetometers
  +@defgroup compass Compass/Magnetometers
  @ingroup bycat
  @brief Measure magnetic field to give rotation or heading
  @@ -115,6 +115,9 @@ and is not meant to be installed anywhere.
  @ingroup bycat
  @brief Provide positioning capabilities
  +@defgroup gyro Gyroscopes
  +@ingroup bycat
  +@brief Measure rotation rate in one or more axes
  @defgroup led LEDs
  @ingroup bycat
  