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]
- niklasfasching/go-org#53
- niklasfasching/go-org@5dadf8c (comment)
- niklasfasching/go-org#51

markup/org/convert.go

@@ -52,7 +52,6 @@ func (c *orgConverter) Convert(ctx converter.RenderContext) (converter.Result, e
 		return afero.ReadFile(c.cfg.ContentFs, filename)
 	}
 	writer := org.NewHTMLWriter()
-	writer.PrettyRelativeLinks = !c.cfg.Cfg.GetBool("uglyURLs")
 	writer.HighlightCodeBlock = func(source, lang string, inline bool) string {
 		highlightedSource, err := c.cfg.Highlight(source, lang, "")
 		if err != nil {