docs: Add warning notes

MMMzq · web-flow · commit c53079ece221 · 2020-10-30T13:25:39.000+08:00
diff --git a/README_zh.md b/README_zh.md
@@ -75,6 +75,7 @@ MaterialApp(
 ```
 or
 ``` dart
+//警告:不要随意调整调用BotToastInit函数的位置
 final botToastBuilder = BotToastInit();  //1.调用BotToastInit
 MaterialApp(
       title: 'BotToast Demo',
