data/defaults.yaml: Add missing instruction to update swh-web configuration
data/defaults.yaml: Add missing instruction to update swh-web configuration

Related T1976

SoftwareHeritage/puppet-swh-site,SoftwareHeritage/puppet-swh-site,SoftwareHeritage/puppet-swh-site,SoftwareHeritage/puppet-swh-site,SoftwareHeritage/puppet-swh-site