flag contact email adress as optional

.env.tpl

@@ -99,8 +99,9 @@ NOPAQUE_ADMIN_EMAIL_ADRESS=
 # CHOOSE ONE: development, production, testing
 # NOPAQUE_CONFIG=
 
+# DEFAULT: None
 # EXAMPLE: contact.nopaque@example.com
-NOPAQUE_CONTACT_EMAIL_ADRESS=
+# NOPAQUE_CONTACT_EMAIL_ADRESS=
 
 # DEFAULT: /mnt/nopaque
 # NOTE: This must be a network share and it must be available on all Docker Swarm nodes