/usr/share/doc/ is in iptables 1.4.12-1ubuntu4.
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/usr/share/doc-base/packet-filter
/usr/share/doc-base/nat
/usr/share/doc/iptables/
/usr/share/doc/iptables/copyright
/usr/share/doc/iptables/html/
/usr/share/doc/iptables/html/packet-filtering-HOWTO-2.html
/usr/share/doc/iptables/html/NAT-HOWTO.html
/usr/share/doc/iptables/html/NAT-HOWTO-9.html
/usr/share/doc/iptables/html/NAT-HOWTO-2.html
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/usr/share/doc/iptables/html/NAT-HOWTO-10.html
/usr/share/doc/iptables/html/packet-filtering-HOWTO-9.html
/usr/share/doc/iptables/changelog.Debian.gz
/usr/share/doc/iptables/README.Debian