Added comment to clarify FQDN regex
Added comment to clarify FQDN regex

letsencrypt/letsencrypt,kuba/letsencrypt,twstrike/le_for_patching,lmcro/letsencrypt,thanatos/lets-encrypt-preview,goofwear/letsencrypt,martindale/letsencrypt,VladimirTyrin/letsencrypt,goofwear/letsencrypt,xgin/letsencrypt,brentdax/letsencrypt,piru/letsencrypt,stweil/letsencrypt,jsha/letsencrypt,VladimirTyrin/letsencrypt,mrb/letsencrypt,mitnk/letsencrypt,DavidGarciaCat/letsencrypt,piru/letsencrypt,bsmr-misc-forks/letsencrypt,stweil/letsencrypt,Sveder/letsencrypt,lbeltrame/letsencrypt,jsha/letsencrypt,martindale/letsencrypt,lmcro/letsencrypt,dietsche/letsencrypt,TheBoegl/letsencrypt,mitnk/letsencrypt,TheBoegl/letsencrypt,wteiken/letsencrypt,bsmr-misc-forks/letsencrypt,twstrike/le_for_patching,dietsche/letsencrypt,Sveder/letsencrypt,sjerdo/letsencrypt,DavidGarciaCat/letsencrypt,jtl999/certbot,sjerdo/letsencrypt,brentdax/letsencrypt,jtl999/certbot,letsencrypt/letsencrypt,thanatos/lets-encrypt-preview,xgin/letsencrypt,kuba/letsencrypt,wteiken/letsencrypt,mrb/letsencrypt,lbeltrame/letsencrypt