List pairs of source and destination files to register with ucf. Each pair
should be put on its own line, with the source and destination separated by
whitespace. Both source and destination must be absolute paths. The source
should be a file that is provided by your package, typically in /usr/share/,
while the destination is typically a file in /etc/.
A dependency on ucf will be generated in ${misc:Depends}.
Supports substitution variables in compat 13 and later as
documented in debhelper(7).