The Debian changelog file is a symlink to a file in a different directory or not found in this package. Please don't do this. It makes package checking and manipulation unnecessarily difficult. Because it was a symlink, the Debian changelog file was not checked for other problems. (Symlinks to another file in /usr/share/doc/pkg or a subdirectory thereof are fine and should not trigger this warning.)
To refer to the changelog, copyright, and other documentation files of another package that this one depends on, please symlink the entire /usr/share/doc/pkg directory rather than individual files.