Hello,If it helps in any way, the documentation in sed-4.4 (included in 'stretch') as licensed under GFDLv1.3 and explicitly states:
"with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts." http://git.savannah.gnu.org/cgit/sed.git/tree/doc/sed.texi#n39 regards, - assaf