Documentation is not included in the Debian package for Autoconf because the Debian project has decided that the GNU FDL is not an acceptable license for documentation. If you disagree with this decision, write to debian-legal@lists.debian.org. I can't do anything about it by myself, so filing bugs will do you no good. Sorry.
If you are connected to the Internet, you can view the documentation for Autoconf 2.57 online. This is a slightly outdated version of the documentation but it should be largely correct.