docs: add vue router tips

[screetBloom]

Checklist

• npm test passes
• tests are included
• documentation is changed or added
• commit message follows commit guidelines

Description of change

add a FAQ about Vue Router

Some background information：

• I'm having some problems when use vue router in qiankun. I hope I can share some of my experience with others.
• And this is my first contribution to qiankun, I am eager to get this merged . Thx~

@kuitos

[screetBloom]

Some checks were not successful !
But this looks like it's due to an external cause 👇.

[kuitos]

补充一下英文文档部分？

[kuitos]

merge with master then the ci failure will gone

[screetBloom]

补充一下英文文档部分？

好的，收到

[screetBloom]

我使用 sub-app 的原因：https://en.wiktionary.org/wiki/subapplication

根据wiki来看，应该是subapplication 或者 sub-app

@kuitos 你看一下是否认可，如果不认可的话我快速改一下

[kuitos]

Thanks for your nice work!