For what I understand ulimit is not a binary installed by any package but is a shell function. While you type man ulimit you are seeing only what -f option is able to do. While you type man bash or man dash you can find a complete documentation about ulimit. So I'm asking if is right to show the manpage which contains only -f option instead of point to the manual of the actual shell the user is using.
there is no ulimit(1) man page, so man-pages doesn't install it there is a ulimit(1p) man page which is specified by POSIX, so the man-pages-posix package includes it and that's to be expected
