activeMatch只生效于展开菜单内

https://github.com/vuejs/vitepress/issues/4163

点击navbar的Examples里面的test，然后点击sidebar的test1，此时Examples为红色高亮。但是，点击sidebar的test2时，Examples不为红色高亮。

Click on test in Examples of navbar and then click on test1 of sidebar with Examples highlighted in red. However, when you click on test2 of the sidebar, Examples are not highlighted in red.

如下图