[vtkusers] About vtkPoints::InsertPoint()

[David Doria]

This is just more evidence for the confusion that the TCL installer
causes. David DeMarle updated the text on the last release:
http://www.vtk.org/VTK/resources/software.html#cand

which helps a lot, but it is still the first thing in the download
list, and is the only link that is an "installer". Windows users will
likely not be familiar with the concept of using something that does
not come with an "installer". It needs to be made much more clear that
in almost all cases VTK must be built from source, and not installed
with the exe installer.

David