[dns|examples] fix deprecated record#ip= usage

examples/dns_tests.rb

@@ -35,7 +35,7 @@ Shindo.tests('dns examples', 'dns') do
       #   type is the type of record to create
       tests('@record = @zone.records.create').succeeds do
         @record = @zone.records.create(
-          :ip => '1.2.3.4',
+          :value  => '1.2.3.4',
           :name   => 'www.fogdnsexamples.com',
           :type   => 'A'
         )