Merge branch 'doc/update-parameterlist' into 'master'

Doc/update parameterlist

Closes #956

See merge request dumux-repositories/dumux!2340

(cherry picked from commit 8173c933)

bafb7185 [doxygen] Update parameterlist.
6e08784a [doc] Minor improvments of documentation.
98f328d4 [doc][doxygen] Improvements to parameterlist.txt.