/etc/asterisk/manager.d/README.conf is in asterisk-config 1:11.13.1~dfsg-2+deb8u5.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 | ; Empty placeholder by the Debian packaging.
; You can add manager users by dropping files with a .conf extension in
; this directory.
|