add readme for pay starter

starters/wx-java-pay-starter/README.md

@@ -0,0 +1,27 @@
+# 使用说明
+1. 在自己的Spring Boot项目里，引入maven依赖
+```xml
+    <dependency>
+        <groupId>com.github.binarywang</groupId>
+        <artifactId>wx-java-pay-starter</artifactId>
+        <version>${version}</version>
+    </dependency>
+ ```
+2. 添加配置(application.yml)
+```yml
+wx:
+  pay:
+    appId: wx5b69c56ac01ed858
+    mchId: 1462547202
+    mchKey: OGL9fvig9y2HrXrQ86tM4jTwyv4ja6G5
+    subAppId:
+    subMchId:
+    keyPath:
+```
+
+
+
+
+
+
+