FEATURE: allow users to specify a second hostname if needed

(very rarely needed feature, mostly for multisite and origin pull cdns)

config/discourse_defaults.conf

@@ -46,6 +46,9 @@ db_prepared_statements = true
 # hostname running the forum
 hostname = "www.example.com"
 
+# backup hostname
+hostname2 =
+
 # address of smtp server used to send emails
 smtp_address =