Entity增加camelCase属性

docs/sqlsource.md

@@ -22,7 +22,7 @@
 ```sql
     DELETE FROM user WHERE user_name = $${bean.userName}
 ```
-  当bean.userName=null时，执行sql会报错 ```Missing parameter bean.userName```
+  当bean=null或者bean.userName=null时，执行sql会报错 ```Missing parameter bean.userName```
 
   Service调用原生SQL模板示例：
 ```java