Missing documents / broken links

There are a few broken links to documents on the webpage:

• https://www.dune-project.org/modules/dune-foamgrid/dicr-intersections-for-network-grids.pdf
• http://users.dune-project.org/projects/redesign-of-dune-grid-intersections

Found on the module page: https://www.dune-project.org/modules/dune-foamgrid/