I installed http://packages.ubuntu.com/zesty/emacs which includes Gnus, but there's no
/usr/share/info/gnus.info.gz – am I forced to use the web wowser to read the fine manual, or is there some simple way to get the info file?
According to the package database, you can find
/usr/share/info/emacs-25/gnus.info.gz, along with a lot of other info manuals.
4Correct. Debian (and Ubuntu by derivation) package Gnu documentation in separate packages, as the Gnu documentation license conflicts with the Debian Free Software Guidelines. Usually these packages are in the non-free repo, and have the
non-dfsgsuffix on the package name.– TylerApr 20, 2017 at 16:38