update docs/univerify.md.

添加全屏支持描述

docs/univerify.md

@@ -13,6 +13,19 @@
 
 ![](https://dcloud-img.oss-cn-hangzhou.aliyuncs.com/client/doc/univerify/demo.png)
 
+<a id="fullscreen"/>
+> HBuilderX3.1.6+版本授权登录界面支持全屏模式
+调用uni.login时设置univerifyStyle中的fullScreen属性值为true即可
+```js
+uni.login({
+	provider: 'univerify',
+	univerifyStyle: { 
+            fullScreen: true
+        }
+})
+```
+效果如下:
+![](https://dcloud-img.oss-cn-hangzhou.aliyuncs.com/client/doc/univerify/full.png)
 
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