🎨 完善部分代码注释，修复 yaml 未自动提示 hosts 配置问题

spring-boot-starters/wx-java-mp-multi-spring-boot-starter/src/main/java/com/binarywang/spring/starter/wxjava/mp/properties/WxMpMultiProperties.java

@@ -37,10 +37,19 @@ public class WxMpMultiProperties implements Serializable {
   public static class HostConfig implements Serializable {
     private static final long serialVersionUID = -4172767630740346001L;
 
+    /**
+     * 对应于：https://api.weixin.qq.com
+     */
     private String apiHost;
 
+    /**
+     * 对应于：https://open.weixin.qq.com
+     */
     private String openHost;
 
+    /**
+     * 对应于：https://mp.weixin.qq.com
+     */
     private String mpHost;
   }