enhance the doc of MergeLabelMapFilter
enhance the doc of MergeLabelMapFilter

Change-Id: Ida0d887c4bf95544f1b87f08a433ac98626ca683

rhgong/itk-with-dom,Kitware/ITK,hjmjohnson/ITK,CapeDrew/DCMTK-ITK,heimdali/ITK,malaterre/ITK,vfonov/ITK,CapeDrew/DITK,atsnyder/ITK,CapeDrew/DCMTK-ITK,rhgong/itk-with-dom,stnava/ITK,jcfr/ITK,hendradarwin/ITK,PlutoniumHeart/ITK,fbudin69500/ITK,heimdali/ITK,LucasGandel/ITK,daviddoria/itkHoughTransform,LucHermitte/ITK,itkvideo/ITK,eile/ITK,ajjl/ITK,hinerm/ITK,daviddoria/itkHoughTransform,heimdali/ITK,LucHermitte/ITK,fedral/ITK,hendradarwin/ITK,rhgong/itk-with-dom,spinicist/ITK,malaterre/ITK,spinicist/ITK,paulnovo/ITK,Kitware/ITK,CapeDrew/DCMTK-ITK,Kitware/ITK,cpatrick/ITK-RemoteIO,eile/ITK,ajjl/ITK,eile/ITK,CapeDrew/DITK,LucHermitte/ITK,blowekamp/ITK,eile/ITK,ajjl/ITK,eile/ITK,blowekamp/ITK,jcfr/ITK,GEHC-Surgery/ITK,spinicist/ITK,BRAINSia/ITK,stnava/ITK,spinicist/ITK,daviddoria/itkHoughTransform,thewtex/ITK,fbudin69500/ITK,BRAINSia/ITK,LucasGandel/ITK,GEHC-Surgery/ITK,hendradarwin/ITK,PlutoniumHeart/ITK,msmolens/ITK,cpatrick/ITK-RemoteIO,hjmjohnson/ITK,hjmjohnson/ITK,LucasGandel/ITK,msmolens/ITK,rhgong/itk-with-dom,BlueBrain/ITK,LucHermitte/ITK,zachary-williamson/ITK,InsightSoftwareConsortium/ITK,LucasGandel/ITK,stnava/ITK,itkvideo/ITK,fbudin69500/ITK,PlutoniumHeart/ITK,vfonov/ITK,jcfr/ITK,BlueBrain/ITK,CapeDrew/DCMTK-ITK,LucHermitte/ITK,msmolens/ITK,msmolens/ITK,InsightSoftwareConsortium/ITK,stnava/ITK,cpatrick/ITK-RemoteIO,InsightSoftwareConsortium/ITK,rhgong/itk-with-dom,LucHermitte/ITK,BRAINSia/ITK,fbudin69500/ITK,biotrump/ITK,zachary-williamson/ITK,hjmjohnson/ITK,GEHC-Surgery/ITK,fedral/ITK,richardbeare/ITK,BlueBrain/ITK,heimdali/ITK,hjmjohnson/ITK,CapeDrew/DITK,thewtex/ITK,malaterre/ITK,wkjeong/ITK,vfonov/ITK,cpatrick/ITK-RemoteIO,Kitware/ITK,fedral/ITK,heimdali/ITK,daviddoria/itkHoughTransform,CapeDrew/DITK,biotrump/ITK,CapeDrew/DCMTK-ITK,jcfr/ITK,vfonov/ITK,CapeDrew/DCMTK-ITK,rhgong/itk-with-dom,fedral/ITK,eile/ITK,BRAINSia/ITK,biotrump/ITK,malaterre/ITK,jmerkow/ITK,heimdali/ITK,eile/ITK,hinerm/ITK,hinerm/ITK,CapeDrew/DITK,hendradarwin/ITK,daviddoria/itkHoughTransform,CapeDrew/DCMTK-ITK,itkvideo/ITK,vfonov/ITK,BRAINSia/ITK,hinerm/ITK,daviddoria/itkHoughTransform,Kitware/ITK,blowekamp/ITK,CapeDrew/DITK,BlueBrain/ITK,eile/ITK,paulnovo/ITK,PlutoniumHeart/ITK,fuentesdt/InsightToolkit-dev,daviddoria/itkHoughTransform,BlueBrain/ITK,stnava/ITK,stnava/ITK,hjmjohnson/ITK,heimdali/ITK,malaterre/ITK,blowekamp/ITK,biotrump/ITK,InsightSoftwareConsortium/ITK,msmolens/ITK,vfonov/ITK,LucasGandel/ITK,BlueBrain/ITK,LucHermitte/ITK,richardbeare/ITK,cpatrick/ITK-RemoteIO,hinerm/ITK,msmolens/ITK,paulnovo/ITK,msmolens/ITK,wkjeong/ITK,daviddoria/itkHoughTransform,paulnovo/ITK,fbudin69500/ITK,itkvideo/ITK,stnava/ITK,jcfr/ITK,GEHC-Surgery/ITK,thewtex/ITK,hendradarwin/ITK,vfonov/ITK,jmerkow/ITK,itkvideo/ITK,BRAINSia/ITK,richardbeare/ITK,biotrump/ITK,itkvideo/ITK,hendradarwin/ITK,daviddoria/itkHoughTransform,ajjl/ITK,wkjeong/ITK,fedral/ITK,spinicist/ITK,ajjl/ITK,msmolens/ITK,spinicist/ITK,Kitware/ITK,blowekamp/ITK,richardbeare/ITK,LucasGandel/ITK,hjmjohnson/ITK,atsnyder/ITK,itkvideo/ITK,zachary-williamson/ITK,blowekamp/ITK,paulnovo/ITK,rhgong/itk-with-dom,CapeDrew/DCMTK-ITK,vfonov/ITK,BlueBrain/ITK,jmerkow/ITK,richardbeare/ITK,fuentesdt/InsightToolkit-dev,zachary-williamson/ITK,itkvideo/ITK,BlueBrain/ITK,jmerkow/ITK,spinicist/ITK,cpatrick/ITK-RemoteIO,jcfr/ITK,spinicist/ITK,CapeDrew/DITK,thewtex/ITK,jmerkow/ITK,fuentesdt/InsightToolkit-dev,ajjl/ITK,zachary-williamson/ITK,wkjeong/ITK,fuentesdt/InsightToolkit-dev,atsnyder/ITK,hinerm/ITK,GEHC-Surgery/ITK,atsnyder/ITK,zachary-williamson/ITK,richardbeare/ITK,rhgong/itk-with-dom,Kitware/ITK,zachary-williamson/ITK,PlutoniumHeart/ITK,spinicist/ITK,malaterre/ITK,GEHC-Surgery/ITK,hendradarwin/ITK,atsnyder/ITK,thewtex/ITK,fuentesdt/InsightToolkit-dev,cpatrick/ITK-RemoteIO,atsnyder/ITK,CapeDrew/DITK,thewtex/ITK,fuentesdt/InsightToolkit-dev,richardbeare/ITK,wkjeong/ITK,fbudin69500/ITK,ajjl/ITK,BRAINSia/ITK,atsnyder/ITK,malaterre/ITK,fbudin69500/ITK,PlutoniumHeart/ITK,PlutoniumHeart/ITK,jmerkow/ITK,GEHC-Surgery/ITK,CapeDrew/DCMTK-ITK,wkjeong/ITK,atsnyder/ITK,jcfr/ITK,hinerm/ITK,zachary-williamson/ITK,fedral/ITK,LucHermitte/ITK,paulnovo/ITK,fedral/ITK,itkvideo/ITK,biotrump/ITK,paulnovo/ITK,eile/ITK,thewtex/ITK,blowekamp/ITK,jmerkow/ITK,InsightSoftwareConsortium/ITK,paulnovo/ITK,biotrump/ITK,CapeDrew/DITK,InsightSoftwareConsortium/ITK,GEHC-Surgery/ITK,InsightSoftwareConsortium/ITK,hendradarwin/ITK,fuentesdt/InsightToolkit-dev,hinerm/ITK,wkjeong/ITK,jmerkow/ITK,PlutoniumHeart/ITK,fedral/ITK,wkjeong/ITK,malaterre/ITK,stnava/ITK,LucasGandel/ITK,stnava/ITK,fbudin69500/ITK,fuentesdt/InsightToolkit-dev,biotrump/ITK,cpatrick/ITK-RemoteIO,hinerm/ITK,fuentesdt/InsightToolkit-dev,malaterre/ITK,blowekamp/ITK,jcfr/ITK,LucasGandel/ITK,zachary-williamson/ITK,vfonov/ITK,ajjl/ITK,atsnyder/ITK,heimdali/ITK