The tag is present in Lintian version 2.104.232. That is the most recent version we know about.
The package should not only include the shared library itself, but also the symbolic link which ldconfig would produce. (This is necessary, so that the link gets removed by dpkg automatically when the package gets removed.) If the symlink is in the package, check that the SONAME of the library matches the info in the shlibs file.
Refer to Debian Policy Manual section 8.1 for details.