Several 404-Links on the website

I've found some 404-Links on the website. The 404-Page kindly ask me to report it here. This are the links I've found:

On https://dune-project.org/doc/tutorials/

-> https://dune-project.org/doc/buildsystem/cmakefaq.pdf

-> https://dune-project.org/doc/buildsystem/buildsystem.pdf

-> https://dune-project.org/doc/tutorials/grid-howto.pdf

-> https://dune-project.org/doc/tutorials/refinement.pdf

-> https://dune-project.org/doc/tutorials/istl.pdf

-> https://dune-project.org/doc/tutorials/communication.pdf

-> https://dune-project.org/doc/tutorials/dune-localfunctions-manual.pdf

-> https://dune-project.org/dune-pdelab/files/pdelab-howto-2.0.0.pdf

On https://dune-project.org/doc/installation/

-> https://dune-project.org/modules/dune-module

On https://dune-project.org/doc/install-gmsh/

-> https://dune-project.org/doc/tutorial

-> https://dune-project.org/modules/ext-modules

On https://dune-project.org/dev/downloadgit/

-> https://dune-project.org/dev/contributing_patches

On https://dune-project.org/community/faq/

-> https://www.dune-project.org/flyspray/index.php?do=details&task_id=185