org: Disable broken pretty relative links feature

org: Disable broken pretty relative links feature

go-org PrettyRelativeLinks rewrites relative org links by
- adding `../` in front
- removing any `.org` suffix

This was meant to play well with hugo pretty urls (which pretty much renders
posts in a subdirectory without the file suffix) and allow use of normal org
file links to reference other posts.

There's a lot of edge cases I didn't consider and multiple bug reports in
go-org [1] later I don't think the complexity of handling those edge cases is
worth it - so let's disable it.

[1]
- https://github.com/niklasfasching/go-org/issues/53
- https://github.com/niklasfasching/go-org/commit/5dadf8c4c2924cbb3b93be45f96e1147596ca6f2 (comment)
- https://github.com/niklasfasching/go-org/issues/51