/usr/share/doc/slapd/examples/DB_CONFIG is in slapd 2.4.40+dfsg-1+deb8u4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/slapd/examples/../../../slapd/DB_CONFIG
/usr/share/doc/slapd/examples/../../../slapd/DB_CONFIG