ExternalData: Update documentation to match CMake copy
ExternalData: Update documentation to match CMake copy

Change-Id: Id6dc7c1b665191804641b3796d5ed7728d3c2257

candy7393/VTK,SimVascular/VTK,msmolens/VTK,candy7393/VTK,demarle/VTK,sumedhasingla/VTK,sumedhasingla/VTK,jmerkow/VTK,sankhesh/VTK,mspark93/VTK,demarle/VTK,mspark93/VTK,keithroe/vtkoptix,msmolens/VTK,sumedhasingla/VTK,sankhesh/VTK,msmolens/VTK,gram526/VTK,gram526/VTK,msmolens/VTK,jmerkow/VTK,mspark93/VTK,SimVascular/VTK,SimVascular/VTK,msmolens/VTK,sumedhasingla/VTK,candy7393/VTK,jmerkow/VTK,sumedhasingla/VTK,demarle/VTK,gram526/VTK,gram526/VTK,gram526/VTK,keithroe/vtkoptix,msmolens/VTK,sumedhasingla/VTK,jmerkow/VTK,mspark93/VTK,demarle/VTK,sumedhasingla/VTK,SimVascular/VTK,mspark93/VTK,demarle/VTK,sankhesh/VTK,keithroe/vtkoptix,mspark93/VTK,candy7393/VTK,SimVascular/VTK,jmerkow/VTK,keithroe/vtkoptix,demarle/VTK,sankhesh/VTK,jmerkow/VTK,demarle/VTK,mspark93/VTK,sankhesh/VTK,SimVascular/VTK,keithroe/vtkoptix,keithroe/vtkoptix,jmerkow/VTK,SimVascular/VTK,candy7393/VTK,demarle/VTK,keithroe/vtkoptix,sankhesh/VTK,sankhesh/VTK,candy7393/VTK,candy7393/VTK,gram526/VTK,mspark93/VTK,gram526/VTK,SimVascular/VTK,sumedhasingla/VTK,sankhesh/VTK,jmerkow/VTK,msmolens/VTK,candy7393/VTK,keithroe/vtkoptix,gram526/VTK,msmolens/VTK