DOC: add documentation for the Savitzky-Golay functor

Code/MultiTemporal/otbSavitzkyGolayInterpolationFunctor.h

@@ -21,10 +21,21 @@
 #include "otbTimeSeries.h"
 #include "otbTimeSeriesLeastSquareFittingFunctor.h"
 
+
+
 namespace otb
 {
 namespace Functor
 {
+
+/** \class otbSavitzkyGolayInterpolationFunctor
+
+   * \brief: This functor implements a local polynomial regression (of degree k) on a series of values (of at least k+1 points which are treated as being equally spaced in the series) to determine the smoothed value for each point.
+
+Savitzky, A.; Golay, M.J.E. (1964). "Smoothing and Differentiation of Data by Simplified Least Squares Procedures". Analytical Chemistry 36 (8): 1627–1639. doi:10.1021/ac60214a047
+
+ *
+ */
 template <unsigned int Radius, class TSeries, class TDates, class TWeight = TSeries>
 class SavitzkyGolayInterpolationFunctor
 {