replace mail options reference URL at configuration.yml.example

wiki.rubyonrails.org seems dead.

git-svn-id: http://svn.redmine.org/redmine/trunk@13037 e93f8b46-1217-0410-a6f0-8f06a7374b81

config/configuration.yml.example

@@ -72,10 +72,9 @@
 #
 # === More configuration options
 #
-# See the "Configuration options" at the following website for a list of the
-# full options allowed:
+# See following page:
 #
-# http://wiki.rubyonrails.org/rails/pages/HowToSendEmailsWithActionMailer
+# http://guides.rubyonrails.org/action_mailer_basics.html#action-mailer-configuration
 
 
 # default configuration options for all environments