Man pages matching name ur::datasource::rdbms::fkconstraint in section 3pm:

UR::DataSource::RDBMS::FkConstraint.3pm.en	debian 10 / libur-perl
UR::DataSource::RDBMS::FkConstraint.3pm.en	debian 11 / libur-perl
UR::DataSource::RDBMS::FkConstraint.3pm.en	debian 12 / libur-perl