This file is indexed.

/usr/share/doc/add-apt-key/README is in add-apt-key 1.0-0.5.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

1
2
3
4
5
6
7
8
9
add-apt-key
-----------

This program is intended for Debian (or Debian based
distributions) as a convenient method for adding a 
GPG key to your APT key ring.

This program should be "Debianized" and, as such, is
not intended for direct installation.