- Add support for pretty urls [1]. Rewrite file links:
1. replace the `.org` extension with `/` (`/foo.org` -> `/foo/`)
2. prefix unrooted links with `../` as relative links start in the fake
subdirectory `/foo/` rather than `/`
- Fix case-sensitivity of org drawer `🔚`
[1] https://gohugo.io/content-management/urls/#pretty-urls