submit it as a patch to the docs (they're in markdown) https://libreboot.org/git.html
Since Trisquel is basically Debian (the guide for Debian that we have, also still works on Trisquel), you could just re-add the file encrypted_trisquel.md, with a link for that from gnulinux/index.md, with encrypted_trisquel.md linking (e.g. via http redirect) to encrypted_debian.html
