docs: fix flowchart which is not working (#2010)

Author: SigureMo

packages/docs/docs/.vuepress/config.js

@@ -87,6 +87,7 @@ module.exports = ctx => ({
       before: info => `<UpgradePath title="${info}">`,
       after: '</UpgradePath>',
     }],
+    ['flowchart'],
   ],
   extraWatchFiles: [
     '.vuepress/nav/en.js',

packages/docs/docs/zh/faq/README.md

@@ -12,12 +12,12 @@ sidebar: auto
 
 描述 stylus 编译器编译顺序的简单图表如下：
 
-@flowstart <br />
-阶段1=>操作: palette.styl <br />
-阶段2=>操作: 默认 app 样式 <br />
-阶段3=>操作: index.styl <br />
+@flowstart
+stage1=>operation: palette.styl
+stage2=>operation: 默认 app 样式
+stage3=>operation: index.styl
 
-阶段1->阶段2->阶段3 <br />
+stage1->stage2->stage3
 @flowend
 
 <br>