Bug#674913: sgml-data: do not call update-catalog

[Helmut Grohne <helmut@subdivi.de>]

Package: sgml-data
Version: 2.0.6
Severity: important

Your package calls update-catalog on /etc/sgml/$PACKAGE.cat. The latter
file will transition to a conffile, so changing that file induces
questions to the user. Please remove the old and no longer needed call
to update-catalog.

Helmut