delimiter between domain and additional names in domain.txt is 'space only'

[KampfCaspar]

If one delimits the 'main' domain name and additional domain names by other whitespace characters (e.g. tab), certificate issuance works fine, but 'cron' age check fails...

This is because 'cut' only accepts one delimiter - space OR tab.

Probably add an explanatory comment line in domains.txt.example?