DOC: add '\ingroup in functors doc

include/otbNDVITimeSeriesFunctor.h

@@ -32,6 +32,8 @@ namespace functor
  * \brief Base class for reducing N-components pixel into M-component pixel (N=nb. of images and M=nb. of years)
  *
  * Dates must be provided in chronological order, else the "SetDates()" method will throw an exception.
+ *
+ * \ingroup NDVITimeSeries
  */
 template< class TInputPixel, class TOutputPixel>
 class TSReduceFunctorBase
@@ -88,6 +90,7 @@ private:
  * \brief Class for reducing N-components pixel into M-component pixel (N=nb. of images and M=nb. of years)
  * given a range (dd/mm--->dd'/mm')
  *
+ * \ingroup NDVITimeSeries
  */
 template< class TInputPixel, class TOutputPixel>
 class TSCumulatedRangeReduceFunctor : public TSReduceFunctorBase<TInputPixel,TOutputPixel>
@@ -155,6 +158,7 @@ int m_Month2;
  * \brief Class for reducing N-components pixel into M-component pixel (N=nb. of images and M=nb. of years)
  * returns for each year the max() value
  *
+ * \ingroup NDVITimeSeries
  */
 template< class TInputPixel, class TOutputPixel>
 class TSMaxReduceFunctor : public TSReduceFunctorBase<TInputPixel,TOutputPixel>
@@ -213,6 +217,7 @@ inline TOutputPixel operator ()(const TInputPixel& input) const
  * \brief Class for reducing N-components pixel into M-component pixel (N=nb. of images and M=nb. of years)
  * returns for each year the max()-min() value
  *
+ * \ingroup NDVITimeSeries
  */
 template< class TInputPixel, class TOutputPixel>
 class TSAmplitudeReduceFunctor : public TSReduceFunctorBase<TInputPixel,TOutputPixel>