cleanup of documentation files

6 jobs for feature/mkdocs in 31 minutes and 21 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
passed #15011
dune-2.6 debian-10 gcc-8-17

00:16:32

passed #15012
dune-2.6 debian-9 gcc-6-14

00:12:37

passed #15013
dune-2.6 ubuntu-18.04 clang-6-17

00:11:30

passed #15014
dune-git debian-10 gcc-8-17

00:26:47

passed #15015
dune-git debian-9 gcc-6-14

00:19:46

passed #15016
dune-git ubuntu-18.04 clang-6-17

00:17:39