README增加使用示例

Author: CandyMi

README.md

@@ -36,4 +36,46 @@
 
   * 查询商户资料
 
-## 待补充
+## 使用示例
+
+```lua
+local cashier = require "cloud.payjs.cashier"
+local native = require "cloud.payjs.native"
+local micro = require "cloud.payjs.micro"
+local face = require "cloud.payjs.face"
+local js = require "cloud.payjs.js"
+local order = require "cloud.payjs.order"
+local utils = require "cloud.payjs.utils"
+
+local mchid = "123456"
+local key = "wodjwaiodwadka"
+
+-- 支付相关接口
+-- js.pay(mchid, key, ...)
+-- native.pay(mchid, key, ...)
+-- cashier.pay(mchid, key, ...)
+-- face.pay(mchid, key, ...)
+
+-- 订单相关接口
+-- order.order_check(mchid, key, order_id)
+-- order.order_close(mchid, key, order_id)
+-- order.order_reverse(mchid, key, order_id)
+-- order.order_refund(mchid, key, order_id)
+
+
+-- 查询商户信息
+-- utils.mch_info(mchid, key)
+
+-- 查询银行编码
+-- utils.bank_code(mchid, key, bank)
+
+-- 获取用户 OPENID
+-- utils.mch_openid(mchid, key, callback_url)
+```
+
+
+## 协议
+
+  [MIT](https://github.com/CandyMi/payjs-lua/blob/master/LICENSE)
+
+