/usr/share/doc/libpangomm-1.4-1v5/README is in libpangomm-1.4-1v5 2.40.1-4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2
This is pangomm, a C++ API for Pango. See http://www.gtkmm.org/