Fix some errors for flattenicityTask

Author: PaolaVT

PWGMM/UE/Tasks/flattenicityTask.cxx

@@ -1,3 +1,8 @@
+/// \file flattenicityTask.cxx
+/// \brief Flattenicity analysis task for UE studies
+/// \author Eisha Rani
+/// \since August 2026
+
 // Copyright 2019-2020 CERN and copyright holders of ALICE O2.
 // See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
 // All rights not expressly granted are reserved.
@@ -9,11 +14,6 @@
 // granted to it by virtue of its status as an Intergovernmental Organization
 // or submit itself to any jurisdiction.
 
-/// \file flattenicityTask.cxx
-/// \brief Flattenicity analysis task for UE studies
-/// \author Eisha Rani
-/// \since August 2026
-
 #include "Common/Core/TrackSelection.h"
 #include "Common/Core/TrackSelectionDefaults.h"
 #include "Common/DataModel/EventSelection.h"