[vtkusers] VTK build instructions cleanup

[Florian Rist]

Hi David

> We strongly encourage everyone to use CMake to create their projects
> so that none of that is necessary.

Oh, I forgot, and I have to admit, I haven't tried the CMake approach, 
jet. I'll give it a try tomorrow.

 > However, if you'd like to add a "How to include VTK in your project
 > with CMake" page somewhere, that might be useful for some people in
 > rare cases.

...with_out_ CMake... Right?

Indeed, especially since there are lot of tutorials on this topic out 
here giving - to my option - false advice, like copying header files or 
libraries to the project etc.

Flo