/usr/lib/erlang/lib/reltool-0.7/info is in erlang-doc 1:18.3-dfsg-1ubuntu3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/erlang/lib/reltool-0.7/../../../../share/doc/erlang-doc/lib/reltool-0.7/info