Allow `path` to be merged into route config

[yaquawa]

There is no way to specify a dynamic path with regular expression. I expect this will work, but it won't.

<route>
{
  path: "/:category(foo|bar|baz)"
}
</route>

can we merge the path as well?

[ktsn]

What is the use case for that?

[yaquawa]

@ktsn There is no way to specify a dynamic path with regular expression, currently you have to modify the generated routes. https://next.router.vuejs.org/guide/essentials/route-matching-syntax.html#custom-regexp-in-params