Support custom base path for local files

[pmwmedia]

I use Hugo for generating my static HTML files. After the generation, I want to check all links. The peculiarity is that all internal links start with /v2 as base path. but stored locally in a folder named public.

Folder structure:

public/index.html      <-- internal link: /v2/
public/foo/index.html  <-- internal link: /v2/foo/
public/bar/index.html  <-- internal link: /v2/bar/

Now, I would like to tell linkinator via cli that it should map /v2/ to public/index.html, /v2/foo/ to public/foo/index.html and so on.