文档优化

@@ -40,10 +40,12 @@ Please set the width and height of the design draft before use, the width and he
 Be sure to set the page in the MaterialApp's home(ie the entry file, just set it once) to ensure that the fit size is set before each use:
 
 ```
+
+//fill in the screen size of the device in the design
+
 //default value : width : 1080px , height:1920px , allowFontScaling:false
 ScreenUtil.instance = ScreenUtil()..init(context);
 
-//fill in the screen size of the device in the design
 //If the design is based on the size of the iPhone6 ​​(iPhone6 ​​750*1334)
 ScreenUtil.instance = ScreenUtil(width: 750, height: 1334)..init(context);
 

@@ -45,10 +45,12 @@ import 'package:flutter_screenutil/flutter_screenutil.dart';
 一定在MaterialApp的home中的页面设置(即入口文件，只需设置一次),以保证在每次使用之前设置好了适配尺寸:
 
 ```
+//填入设计稿中设备的屏幕尺寸
+
 //默认 width : 1080px , height:1920px , allowFontScaling:false
 ScreenUtil.instance = ScreenUtil()..init(context);
 
-//填入设计稿中设备的屏幕尺寸 , 假如设计稿是按iPhone6的尺寸设计的(iPhone6 750*1334) 
+//假如设计稿是按iPhone6的尺寸设计的(iPhone6 750*1334) 
 ScreenUtil.instance = ScreenUtil(width: 750, height: 1334)..init(context);
 
 //设置字体大小根据系统的“字体大小”辅助选项来进行缩放,默认为false : 字体不随着系统的“字体大小”辅助选项来进行缩放