Document CN pattern for SupAnn
The SupAnn standard specifies how to fill
cn attribute: https://services.renater.fr/documentation/supann/supann2018/recommandations2018/attributs/cn
So we may want to explain in our documentation how to do this in FD.
The simplest pattern for this is
%a|sn% %a|givenName%, but maybe %t|sn% %t|givenName% is better.
%t[fr_FR]|sn% %t[fr_FR]|givenName% to get translit following french rules?