Update examples to show that zone_names is handles

Author: fformica

ns1/examples/alert.tf

@@ -6,7 +6,7 @@ resource "ns1_alert" "example1" {
 
   #optional
   notification_lists = []
-  zone_names = []
+  zone_names = ["a.b.c.com","myzone"]
   record_ids = []
 }
 

website/docs/r/alert.html.markdown

@@ -21,7 +21,7 @@ resource "ns1_alert" "example1" {
 
   #optional
   notification_lists = []
-  zone_names = ["a.b.c.com"]
+  zone_names = ["a.b.c.com","myzone"]
   record_ids = []
 }