fix(): update email signatures

api/desecapi/templates/emails/domain-dyndns/content.txt

@@ -31,11 +31,11 @@ Cheers,
 Nils
 
 --
-deSEC GbR
+deSEC
 Maybachufer 9
 12047 Berlin
 Germany
 
 phone: +49-30-47384344
 
-Vertreten durch: Jan Binger, Peter Thomassen, Nils Wisiol
+Vertreten durch: Dr. Peter Thomassen, Nils Wisiol

api/desecapi/templates/emails/donation/donor-content.txt

@@ -14,6 +14,15 @@ appearing on your bank statement.
 
 Again, thank you so much.
 
+Cheers,
+Nils
+
 --
-Nils Wisiol
 deSEC
+Maybachufer 9
+12047 Berlin
+Germany
+
+phone: +49-30-47384344
+
+Vertreten durch: Dr. Peter Thomassen, Nils Wisiol