Fixing the site url

mkdocs.yml

 # Change these to reflect the user and site details.
 site_name: vtk-examples
-site_url: https://kitware.github.io/vtk-examples/site/
+site_url: https://examples.vtk.org/site/
 repo_name: Kitware/vtk-examples
 repo_url: https://github.com/Kitware/vtk-examples