[Bug report] resolveRoute does not support relative path

[Mister-Hope]

Description

resolveRoute should support relative path, just like router.resolve()

E.g.:

// at /page/a.html
resolve('b.html') // should be /page/b.html
resolve('../') // should be /

Why this is needed

prev and next links are based on current route path, as people just set relative links like ./a.md and ../