增加阿里云免费20G告警示例，限制username是aliyun1和aliyun2

server/config.json

@@ -45,12 +45,6 @@
 			"interval": 300,
 			"type": "https"
 		},
-		{
-			"name": "aliyun",
-			"host": "https://www.aliyun.com",
-			"interval": 300,
-			"type": "https"
-		},
 		{
 			"name": "114",
 			"host": "114.114.114.114:53",
@@ -84,11 +78,17 @@
 			"callback": "https://yourSMSurl"
 		},
 		{
-			"name": "month traffic warning",
+			"name": "month 999GB traffic warning",
 			"rule": "(network_out-last_network_out)/1024/1024/1024>999",
 			"interval": 3600,
 			"callback": "https://yourSMSurl"
 		},
+		{
+			"name": "aliyun china free 18GB traffic warning",
+			"rule": "(network_out-last_network_out)/1024/1024/1024>18&(username='aliyun1'|username='aliyun2')",
+			"interval": 3600,
+			"callback": "https://yourSMSurl"
+		},
 		{
 			"name": "you can parse an expression combining any known field",
 			"rule": "load_5>3",