broken links.

[zander]

in 80921fb the file platform-linux.md was removed, but there are still several files that link to it;

$ git grep -l platform-linux.md

installation-linux-deb.md
installation-linux-gentoo.md
installation-linux-other.md
installation-linux-rpm.md

[slrslr]

I have tried to edit it & pull request, but do not know how to consolidate multiple file patch into single pull request.