Add CREATE USER, GROUP statements as comments

config/sample-config2.yaml

@@ -1,7 +1,10 @@
 # With this sample config the distinction between LDAP-synchronized
 # groups/users from is done by the membership to ldap_user and
 # ldap_group. These two roles have to be defined manally before
-# pg_ldap_sync can run.
+# pg_ldap_sync can run:
+#     CREATE GROUP ldap_group;
+#     CREATE USER ldap_user;
+#
 
 # Connection parameters to LDAP server
 # see also: http://net-ldap.rubyforge.org/Net/LDAP.html#method-c-new